Rapid aspiration thrombectomy system and method

ABSTRACT

An intravascular access system for facilitation of intraluminal medical procedures within the neurovasculature through an access sheath. The system includes an aspiration or support catheter having a flexible, distal luminal portion having an inner diameter defining a lumen extending between a proximal opening at a proximal end of the luminal portion and a distal opening at a distal end of the luminal portion. The catheter has a rigid spine coupled to at least the proximal end of the luminal portion and extending proximally therefrom. The system includes a dilator having a flexible, distal dilator portion sized to be received within the lumen of the luminal portion. Associated systems, devices, and methods of use are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 16/543,215, filed Aug. 16, 2019, which is a continuation ofSer. No. 15/856,979, filed Dec. 28, 2017, now U.S. Pat. No. 10,456,555,issued Oct. 29, 2019, which is a continuation of U.S. application Ser.No. 15/805,673, filed Nov. 7, 2017, now U.S. Pat. No. 10,485,952, issuedNov. 26, 2019, which is a continuation of U.S. application Ser. No.15/015,799, filed Feb. 4, 2016, now U.S. Pat. No. 9,820,761, issued Nov.21, 2017, which claims priority to U.S. Provisional Application Ser. No.62/111,481, filed Feb. 4, 2015, and U.S. Provisional Application Ser.No. 62/142,637, filed Apr. 3, 2015, the disclosures are eachincorporated by reference herein in their entireties.

This application is also related to the following U.S. PatentApplications, which are incorporated by reference in their entirety: (1)U.S. patent application Ser. No. 14/576,953, filed Dec. 19, 2014; and(2) U.S. patent application Ser. No. 14/569,365, filed Dec. 12, 2014;(3) U.S. patent application Ser. No. 14/537,316, filed Nov. 10, 2014;(4) U.S. patent application Ser. No. 14/221,917, filed Mar. 21, 2014,which are all incorporated by reference.

BACKGROUND

The present disclosure relates generally to medical methods and devicesfor the treatment of acute ischemic stroke. More particularly, thepresent disclosure relates to methods and systems for navigating complexanatomy to perform rapid and safe aspiration and removal of cerebralocclusions.

Acute ischemic stroke is the sudden blockage of adequate blood flow to asection of the brain, usually caused by thrombus or other emboli lodgingor forming in one of the blood vessels supplying the brain. If thisblockage is not quickly resolved, the ischemia may lead to permanentneurologic deficit or death. The timeframe for effective treatment ofstroke is within 3 hours for intravenous (IV) thrombolytic therapy and 6hours for site-directed intra-arterial thrombolytic therapy or up to 8hours for interventional recanalization of a blocked cerebral artery.Re-perfusing the ischemic brain after this time period has no overallbenefit to the patient, and may in fact cause harm due to the increasedrisk of intracranial hemorrhage from fibrinolytic use. Even within thistime period, there is strong evidence that the shorter the time periodbetween onset of symptoms and treatment, the better the results.Unfortunately, the ability to recognize symptoms, deliver patients tostroke treatment sites, and finally to treat these patients within thistimeframe is rare. Despite treatment advances, stroke remains the thirdleading cause of death and the leading cause of serious, long-termdisability in the United States.

Endovascular treatment of acute stroke is comprised of either theintra-arterial administration of thrombolytic drugs such as recombinanttissue plasminogen activator (rtPA), mechanical removal of the blockage,or a combination of the two. As mentioned above, these interventionaltreatments must occur within hours of the onset of symptoms. Bothintra-arterial (IA) thrombolytic therapy and interventional thrombectomyinvolve accessing the blocked cerebral artery via endovasculartechniques and devices.

Like IV thrombolytic therapy, IA thrombolytic therapy alone has thelimitation in that it may take several hours of infusion to effectivelydissolve the clot. Interventional thrombectomy therapies have involvedcapturing and removing the clot using snares, coils or temporary stents(also known as retrievable stent devices), and suctioning the clot withor without adjunct disruption of the clot. Retrievable stent devices arealso utilized to restore flow quickly to the vessel during theintervention. Hybrid procedures are also utilized, combining retrievablestent devices and aspiration via the guide catheter or via intermediatecatheters to aid in the removal of the clot and reduce the risk ofdistal emboli. Finally, balloons or stents have been used to create apatent lumen through the clot when clot removal or dissolution was notpossible.

To access the cerebral anatomy, guide catheters or guide sheaths areused to guide interventional devices to the target anatomy from anarterial access site, typically the femoral artery. Balloon guidecatheters are often used to enable proximal carotid artery occlusionduring periods of the procedure which may potentially liberate a highlevel of emboli. The proximal occlusion has the effect of arrestingforward flow and increasing aspiration efficiency through the lumen ofthe guide catheter. The length of the guide is determined by thedistance between the access site and the desired location of the guidedistal tip. Interventional devices such as guidewires, microcatheters,and intermediate catheters used for sub-selective guides and aspiration,are inserted through the guide and advanced to the target site. Often,devices are used in a co-axial fashion, namely, a guidewire inside amicrocatheter inside an intermediate catheter is advanced as an assemblyto the target site in a stepwise fashion with the inner, most atraumaticelements, advancing distally first and providing support for advancementof the outer elements. The length of each element of the coaxialassemblage takes into account the length of the guide, the length ofproximal connectors on the catheters, and the length needed to extendfrom the distal end. Thus, for example, the working length of anintermediate catheter is typically 20-40 cm longer than the workinglength of a guide, and the working length of a microcatheter istypically 10-30 cm longer than the working length of the intermediatecatheter. The guidewire is typically longer than the microcatheter byanother 20-50 cm.

Some exemplary issues with current technology include the time requiredor even the ability to access the site of the occlusion, the timerequired to restore flow or the inability to fully, or even partially,restore flow to the vessel, the occurrence of distal emboli during theprocedure, which has potentially negative neurologic effect andprocedural complications such as perforation and intracerebralhemorrhage. There is a need for a system of devices and methods thatenable rapid access, optimized aspiration of the clot, distal protectionthroughout all stages of the procedure, which potentially liberateemboli, and safe and rapid exchange of devices as needed to fullyrestore flow to the blocked cerebral vessel.

SUMMARY

In one aspect, there is disclosed an intravascular access system forfacilitation of intraluminal medical procedures within theneurovasculature through an access sheath. The system includes anaspiration or support catheter having a flexible, distal luminal portionhaving an inner diameter defining a lumen extending between a proximalopening at a proximal end of the luminal portion and a distal opening ata distal end of the luminal portion. The catheter has a rigid spinecoupled to at least the proximal end of the luminal portion andextending proximally therefrom. The system includes a dilator having aflexible, distal dilator portion sized to be received within the lumenof the luminal portion; and a rigid, dilator spine extending proximallyfrom the dilator portion.

The dilator spine can align side-by-side with the spine of the catheter.The distal dilator portion can have a tapered distal tip. The dilatorcan have a length at least as long as a length of the catheter such thata distal tip of the dilator protrudes from the distal opening of theluminal portion. The dilator can be generally tubular along at least aportion of the length. A proximal end of the catheter spine can includea gripping feature configured for a user to grasp in order to move thecatheter through an access sheath. A proximal end of the dilator spinecan include a tab configured to be locked with the gripping feature onthe catheter spine. When the catheter and the dilator are in a lockedconfiguration they can be advanced as a single unit through the accesssheath. The gripping feature and the dilator tab can be removablycoupled such that in a locked configuration the dilator tab engages thegripping feature and in an unlocked configuration the dilator tabdisengages from the gripping feature. The dilator tab can be affixed tothe dilator or can be slideable on the dilator to accommodate differentrelative positions between the dilator and the catheter. The distaldilator portion can include one or more detents on an outer surfaceconfigured to lock with correspondingly-shaped surface features on aninner surface of the luminal portion lumen through which the dilatorportion extends. The dilator spine and the catheter spine can have asimilar stiffness and kink-resistance. The dilator can have a visualmarker on a distal end and/or a proximal end of the distal tip. A distalend region of the dilator can be more flexible and increasingly stiffentowards a proximal end region of the dilator. The catheter spine anddilator spine can be configured to cause bi-directional sliding movementof the luminal portion through a lumen of an access sheath and navigatethe luminal portion into a cerebral vessel to reach a treatment site.

In an interrelated aspect, disclosed is an intravascular access systemfor facilitation of intraluminal medical procedures within theneurovasculature having an access sheath and an aspiration or supportcatheter. The access sheath has a sheath body having an inner diameterdefining a lumen between a proximal end and a distal end of the sheathbody. The sheath body has at least one opening from the lumen near adistal end region of the sheath body. The aspiration or support catheterincludes a flexible, distal luminal portion having an outer diametersized for insertion through the lumen of the access sheath, an innerdiameter defining a lumen extending between a proximal opening at aproximal end of the luminal portion and a distal opening at a distal endof the luminal portion, and a length between the proximal opening andthe distal opening. The aspiration or support catheter includes a rigidspine coupled to at least the proximal end of the luminal portion andextending proximally therefrom. The rigid spine is configured to causebi-directional sliding movement of the luminal portion through the lumenof the access sheath and out the at least one opening to navigate theluminal portion into a cerebral vessel to reach a treatment site. Aportion of the outer diameter of the luminal portion fluidly seals withthe inner diameter of the access sheath when the distal end of theluminal portion extends into the cerebral vessel to reach the treatmentsite.

The luminal portion and the sheath body can be concentrically alignedand the lumen of the luminal portion and the lumen of the sheath bodyform a contiguous aspiration lumen from the distal end of the luminalportion to the proximal end of the sheath body. The contiguousaspiration lumen can be used to aspirate fluid and debris from thedistal opening of the luminal portion. The contiguous aspiration lumencan be to deliver materials through the distal opening of the luminalportion. The contiguous aspiration lumen can form a step-up in diameterwhere the lumen of the luminal portion empties into the lumen of thesheath body. The lumen of the luminal portion can be shorter than thelumen of the sheath body. The luminal portion and the sheath body canform an overlap region when the luminal portion extends distally beyondthe at least one opening of the sheath body. The outer diameter of theluminal portion can approach the inner diameter of the lumen of thesheath body such that a seal is formed by the overlap region. The sealcan be configured to enable sealing against a vacuum of up to 25 inHg,or up to 28 inHg. The seal within the overlap region can be configuredto enable sealing against a pressure of up to 300 mmHg or up to 600 orup to 700 mmHg. The seal can be located distal a proximal end of theluminal portion and proximal to the at least one opening of the sheathbody.

The system can further include a sealing element positioned on anexternal surface of the luminal portion. The sealing element can includea stepped up diameter or protruding feature in the overlap region. Thesealing element can include one or more external ridge features. The oneor more ridge features can be compressible when the luminal portion isinserted into the lumen of the sheath body. The sealing element caninclude one or more inclined surfaces biased against an inner surface ofthe sheath body lumen. The sealing element can include one or moreexpandable members actuated to seal. The sheath body can have an outerdiameter suitable for insertion into the carotid artery. The outerdiameter of the sheath body can be between 5Fr and 7Fr.

The sheath body can have a length between the proximal end and thedistal end suitable for locating the distal end of the sheath body atthe petrous portion of an internal carotid artery from a transfemoralapproach. The length of the sheath body can be between 80 cm and 105 cm.The length of the luminal portion can be between 10 cm and 25 cm. Thelength of the luminal portion can be less than a length of the sheathbody such that as the catheter is retracted into the sheath body a sealremains between an overlap region of the luminal portion and the innerdiameter of the sheath body.

The spine can be longer than an entire length of the sheath body. Theluminal portion can include three or more layers including an innerlubricious liner, a reinforcement layer, and an outer jacket layer. Theouter jacket layer can be composed of discreet sections of polymer withdifferent durometers, compositions, and/or thicknesses to vary theflexibility along the length of the distal luminal portion. The outerdiameter of the distal luminal portion can be sized for navigation intocerebral arteries. The inner diameter of the distal luminal portion canbe between 0.040″ and 0.088″. The outer diameter of the luminal portioncan approach the inner diameter of the sheath body creating a sealedarea at an overlap region while still allowing the catheter to movethrough the sheath body. The catheter can be tapered towards the distalopening such that a distal-most end of the luminal portion has a smallerouter diameter compared to a more proximal region of the luminal portionnear where the luminal portion seals with the sheath body. The distalend region of the sheath body can include an occlusion element. Thedistal end region of the sheath body can include an expanding distaltip. The at least one opening from the lumen can include a side openinglocated a distance away from a distal tip of the sheath body. The distaltip of the sheath body further can include a ramp feature configured todirect at an angulation the catheter away from a longitudinal axis ofthe sheath body lumen out through the at least one opening.

The spine can be longer than an entire length of the sheath body. Thespine can be a wire having an outer dimension from 0.014″ to 0.018″. Thespine can be a hypotube having a guide-wire passageway extendingtherethrough. The spine can be a ribbon having an outer dimension from0.010″ to 0.025″ thick. The ribbon can be curved along at least aportion of an arc. The spine can be configured to rotate the luminalportion around a longitudinal axis of the access sheath. The spine canbe eccentrically coupled to the luminal portion and the spine extendproximally from the luminal portion to outside the proximal end of thesheath body. The proximal end of the luminal portion can have an angledcut. The angled cut can be generally planar or curved. The sheath bodycan have one or more visual markers on the distal end region of thesheath body. The distal luminal portion can have one or more visualmarkers at a distal end region of the luminal portion, a proximal endregion of the luminal portion or both. The one or more visual markers onthe sheath body and the one or more visual markers on the luminalportion can be visually distinct. The spine can have one or more visualmarkers. The one or more visual markers of the spine can indicateoverlap between the distal luminal portion and the sheath body. The oneor more visual markers of the spine can be positioned so that when thevisual marker of the spine is aligned with a portion of the accesssheath, the catheter is positioned at a distal-most position withminimal overlap length needed to create a seal between the catheter andthe sheath body.

The system can further include a dilator having a flexible, distaldilator portion having a distal tip and sized to be received within theluminal portion of the catheter. The dilator can be a tubular elementalong at least a portion of its length. The dilator can be a solid rodformed of malleable material configured to be shaped by a user. Thedilator can further include a rigid, dilator spine extending proximallyfrom the dilator portion. The dilator spine can be coaxial and can havea lumen extending through it. The dilator spine can be eccentric. Whenin use, the dilator spine can align side-by-side with the spine of thecatheter. The distal tip of the dilator can be tapered. The dilator canhave a length at least as long as a length of the catheter such that thedistal tip protrudes from the distal opening of the luminal portion. Aproximal end of the spine can include a gripping feature configured fora user to grasp in order to move the catheter through the access sheath.A proximal end of the dilator spine can include a tab configured to belocked with the gripping feature on the catheter spine. When thecatheter and dilator are in a locked configuration they can be advancedas a single unit through the sheath body. The gripping feature and thedilator tab can be removably coupled such that in a locked configurationthe dilator tab engages the gripping feature and in an unlockedconfiguration the dilator tab disengages from the gripping feature. Thedilator tab can be affixed to the dilator and/or can be slideable on thedilator to accommodate different relative positions between the dilatorand the catheter.

The distal dilator portion can include one or more detents on an outersurface configured to lock with correspondingly-shaped surface featureson an inner surface of the luminal portion lumen through which thedilator portion extends. The dilator spine and the catheter spine canhave a similar stiffness and kink-resistance. The dilator can have avisual marker on a distal end and/or a proximal end of the distal tip. Adistal end region of the dilator can be more flexible and increasinglystiffens towards the proximal end region of the dilator.

The access sheath can further include a connector that connects theproximal end of the sheath body to a proximal hemostasis valve. Theproximal hemostasis valve can have an adjustable opening sized largeenough to allow removal of the catheter without dislodging any clotsthereon. When in use with the access sheath, the rigid spine of thecatheter can extend proximally from the luminal portion through theaccess sheath lumen and out the proximal hemostasis valve of the accesssheath. The connector can provide a connection of the proximal end ofthe sheath body to an aspiration line. The connector can have a largebore inner lumen and connects to a large-bore aspiration line. Theaspiration line can connect to an aspiration source. The aspirationsource can be an active aspiration source. The aspiration line canconnect to a forward drip or flush line. The access sheath can furtherinclude a proximal extension portion such that when the distal luminalportion of the catheter is withdrawn from the sheath body lumen itremains within the proximal extension portion. The inner diameter of theluminal portion can be sized to permit placement of an interventionaldevice through the luminal portion.

Other features and advantages should be apparent from the followingdescription of various implementations, which illustrate, by way ofexample, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a system of devices for accessing andremoving a cerebral occlusion to treat acute ischemic stroke from afemoral artery access site;

FIG. 2A shows components of the system of FIG. 1 in position in apatient from the transfemoral approach to treat the occlusion;

FIG. 2B is a detailed view of a portion of the system of FIG. 2A takenalong circle BB;

FIG. 3 shows components of the system of FIG. 1 being used via atranscarotid access site;

FIG. 4 shows an implementation of an access sheath;

FIG. 5 shows an implementation of a proximal portion of the accesssheath of FIG. 4 provided as a separate, removable component;

FIG. 6 shows an implementation of a connector to minimize flowresistance through the access sheath of FIG. 4 into the proximalportion;

FIG. 7 shows an implementation of an access sheath having an occlusionballoon;

FIGS. 8A-8B show implementations of sealing elements between the accesssheath body and luminal portion of a catheter extending therethrough;

FIG. 9 shows an implementation of a microcatheter and retrievable stentdevice positioned through a spined catheter;

FIGS. 10A-10C show implementations of expandable portions on retrievablestent devices;

FIG. 11 shows an implementation of an aspiration system for use with thesystems described herein;

FIG. 12A shows an implementation of a spined catheter system for usewith the systems described herein;

FIG. 12B shows the spined catheter system of FIG. 12A having a spineddilator extending through a lumen of a spined catheter;

FIG. 12C shows the spined catheter system of FIG. 12A extended through aside opening of an implementation of an access sheath;

FIG. 13 is a cross-sectional view taken about line A-A of FIG. 12B;

FIG. 14 is a cross-sectional view taken about line B-B of FIG. 12B;

FIG. 15A shows an implementation of a spined aspiration catheter-dilatorsystem having a spined catheter and a spined dilator in a lockedconfiguration;

FIG. 15B shows the spined aspiration catheter-dilator system having thespined catheter and the spined dilator in an unlocked configuration;

FIG. 16 shows an implementation of a spined catheter system extendingdistally to an access sheath to treat an embolus in a cerebral vessel.

DETAILED DESCRIPTION

One of the major drawbacks to current acute stroke interventionprocedures is the amount of time required to restore blood perfusion tothe brain. This time includes the time it takes to access the occlusivesite or sites in the cerebral artery, and the time it takes tocompletely remove the occlusion in the artery. Because it is often thecase that more than one attempt must be made to completely remove theocclusion, reducing the number of attempts as well as reducing the timerequired to exchange devices for additional attempts is an importantfactor in minimizing the overall time. Additionally, each attempt isassociated with potential procedural risk due to device advancement inthe delicate cerebral vasculature.

Disclosed herein are methods and devices that enable safe and rapidaccess to the complex neurovascular anatomies of the cerebral andintracranial arteries and removal of the occlusion. The methods anddevices include one or more access devices, catheters, and thrombectomydevices to remove the occlusion. Methods and devices are also disclosedto provide active aspiration and/or passive flow reversal for thepurpose of facilitating removal of the occlusion as well as minimizingdistal emboli. The system offers the user a degree of flow control so asto address the specific hemodynamic requirements of the cerebralvasculature. The systems described herein provide superior ease of usein that a single operator may operate the disclosed systems usingsingle-point continuous aspiration for rapid and safe exchange withoutswitching. The higher efficiency of aspiration force through the systemsdescribed herein reduces distal embolic debris and increases the rate of“one-pass” thrombectomy.

It should be appreciated that while some embodiments are described withspecific regard to aspirating a neurovascular anatomy, the embodimentsare not so limited and may also be applicable to other uses. Forexample, the spined aspiration catheter and one or more components ofthe access systems described herein may be used to deliver workingdevices to a target vessel of a coronary anatomy, or other vasculatureanatomy. It should be appreciated that where the phrase “aspirationcatheter” is used herein that such a catheter may be used for otherpurposes besides or in addition to aspiration, such as the delivery offluids to a treatment site or as a support catheter providing a conduitthat facilitates and guides the delivery or exchange of other devicessuch as a guidewire or interventional devices. Alternatively, the accesssystems need not be limited only to the vasculature can be useful foraccess of other parts of the body outside the vasculature. It shouldalso be appreciated that reference throughout this specification to aparticular feature, structure, configuration, characteristic orimplementation or embodiment may be combined in any suitable manner. Theuse of relative terms throughout the description may denote a relativeposition or direction. For example, “distal” may indicate a firstdirection away from a reference point. Similarly, “proximal” mayindicate a location in a second direction opposite to the firstdirection. However, such terms are provided to establish relative framesof reference, and are not intended to limit the use or orientation of ananchoring delivery system to a specific configuration described in thevarious embodiments below.

FIG. 1 shows a system of devices for accessing and removing a cerebralocclusion to treat acute ischemic stroke from a femoral artery accesssite. The system 100 includes an access sheath 220, sheath dilator 250,guidewire 270, one or more spined aspiration or support catheters 320,dilator 340, microcatheter 400, and a retrievable stent device 500, eachof which will be described in more detail below. Further, the system 100can include one or more arterial access sheath system 200 that includesan access sheath 220, one or more sheath dilators 250 and a sheathguidewire 270. The system 100 can include one or more spined cathetersystems 300 including a spined aspiration or support catheter 320, atapered dilator 340, and alternatively a catheter clearing tool 350. Thespine catheter system 300 can incorporate nested spined catheters toprovide for extended reach into distal sites. The system 100 can includean access sheath system 200, a tapered catheter system 300, amicrocatheter 400, and a retrievable stent device 500.

FIG. 2A shows some elements of the system in position in the patientfrom the transfemoral approach to treat the occlusion. The access sheath220 can be inserted through a femoral artery insertion site positionedwith the distal tip of the access sheath 220 at or near the petrousportion of the internal carotid artery ICA. The spined aspirationcatheter 320 can be positioned with the distal tip at the face of theocclusion in the artery. In some implementations, the access sheath 220can be inserted through a direct puncture in the wall of the commoncarotid artery and advanced into the internal carotid artery rather thanvia a transfemoral approach (see FIG. 3 ).

As seen more clearly in detailed FIG. 2B, the access sheath 220 can havea sheath body 222 and an inner lumen 223 extending between a proximalend and a distal end region of the sheath body 222. The spinedaspiration catheter 320 is sized to extend through the inner lumen 223of the access sheath 220 such that a distal end region of the catheter320 extends beyond a distal end region of the access sheath 220. Thecatheter 320 is shown in FIG. 2B exiting the lumen 223 of the sheathbody 222 through a distal opening 221. It should be appreciated,however, that the sheath body 222 may have one or more side openingsnear a distal end region of the body 222 through which the catheter 320can extend (see FIG. 12C) as will be described in more detail below.

Still with respect to FIG. 2B, the spined aspiration catheter 320 caninclude a relatively flexible, distal luminal portion 322 coupled to astiff and kink-resistant proximal spine 330. The distal luminal portion322 can have an inner lumen 323 extending between a proximal end and adistal end of the luminal portion 322. The lumen 323 of the catheter 320can have a first inner diameter and the lumen 223 of the access sheath220 can have a second, larger inner diameter. The lumens 223, 323 arefluidly connected and contiguous such that fluid flow into and/or out ofthe system is possible, such as by applying suction from an aspirationsource coupled to the system via a connector 226 on the access sheath220. An overlap region 120 between the distal section of the sheath body222 and the luminal portion 322 of the catheter 320 is sized andconfigured to create a seal that enables a continuous aspiration lumenfrom the distal tip region of the spined catheter 320 to the proximalsheath connector 226. If the sheath body 222 has a side opening throughwhich the distal luminal portion 322 of the catheter 320 extends, theseal created at the overlap region 120 between the sheath body 222 andthe luminal portion 322 is located proximal to the side opening.

Key dimensions that affect aspiration force through a tube includeradius (r), pressure (P), viscosity (n) and length (L) whereFlow=Q=πr⁴(ΔP)/8 nL. Changes in radius increase flow to the 4^(th) powerand length is inversely proportional to flow. As will be described inmore detail below, the aspiration catheter has an over-the-wire portionthat is a fraction of the overall distance required to reach the targetsite. This configuration greatly speeds up the time required to retractand re-advance the catheter. Further, the systems described herein canprovide for a markedly increased radius and luminal area for aspirationof the clot and markedly shorter length, particularly compared to priorsystems where the aspiration lumen runs along the entire inner diameterof the aspiration catheter. In the systems described herein, themajority of the aspiration lumen has a radius of the procedural sheath.The catheter 320 is smaller in diameter than the guide, but steps up inluminal diameter upon reaching the lumen of the access sheath 220allowing for a greater aspiration force to be applied to a majority ofthe length of the luminal system. Further, the overall length of thisnarrow diameter region of the catheter 320 is much shorter compared tothe overall length of the access sheath. The proximal spine 330 of thecatheter 320 has a length and structure that extends through the lumen223 of the access sheath 220 to a proximal end of the system such thatit can be used to advance and retract the catheter 320 through the lumen223 of the sheath 220. The spine 330 of the aspiration catheter 320,however, takes up only a fraction of the luminal space the systemresulting in increased luminal area for aspiration. Increased luminalarea for aspiration increases the time it takes to aspirate theocclusion and increases the possibility of removing the occlusion in asingle aspiration attempt. The stepped up luminal diameter alsoincreases the annular area available for forward flushing of contrast,saline, or other solutions while devices such as microcatheters ortapered dilators are coaxially positioned in the spined catheter 320 andaccess sheath 220. This can increase the ease and ability to performangiograms during device navigation.

Current stroke interventions pose a risk of distal emboli beingreleased. During the effort to remove or dissolve clot blockages in thecerebral artery, for example, there is a significant risk of thrombusfragmentation creating embolic particles that can migrate downstreaminto either the occluded vessel or other vessels and compromise cerebralperfusion. In carotid artery stenting procedures (CAS), embolicprotection devices and systems are commonly used to reduce the risk ofembolic material from entering the cerebral vasculature. The types ofdevices include intravascular distal filters, and reverse flow or staticflow systems. Unfortunately, because of the delicate anatomy and accesschallenges as well as the need for rapid intervention, these types ofembolic protection systems are not used in interventional treatment ofacute ischemic stroke. The period of a stroke intervention when flow isrestored is normally considered an important time as the brain is nowbeing perfused by blood. However, it is also a period of embolic risk.While there is blockage in the artery, there is no flow. Therefore anyembolic debris created by crossing the occlusion with guidewire and/ormicrocatheter, or deployment of a retrievable stent device across theocclusion, remains stagnant. However, when flow is restored to theartery, the emboli can now flow antegrade to distal vascularterritories.

A second period of embolic risk occurs when the retrievable stent deviceis being pulled back into the guide or catheter. In prior methods anddevices, aspiration is applied to the intermediate catheter duringretrievable stent device retraction into the catheter, or the catheterand retrievable stent device are pulled back together into the guide,while simultaneously applying aspiration to the guide catheter. Twopoints of aspiration, through the catheter and through the guide, mayboth be utilized to reduce risk of distal emboli during the criticalstep of drawing the occlusion through the guide and out of the patient.Often, two people are required to enable two points of aspiration, oraspiration is performed sequentially from first the catheter and thenthe guide, which may lead to interruption in aspiration or sub-optimalaspiration. In the disclosed systems and methods, reverse flow may beapplied to the target site during device advancement, at the criticaltime of flow restoration, and during the entire time that the occlusionis being removed, with a single point of aspiration.

In an aspect of the disclosure, the level of aspiration may be modifiedfrom a low level to achieve adequate protection from distal emboli, to ahigher level to provide effective aspiration removal of the occlusion.This aspect allows distal protection without high levels of blood loss,yet allows a strong aspiration force as needed to remove the occlusion.

In another aspect, there are disclosed methods and devices foradditionally providing active aspiration or passive retrograde flowduring the procedure to remove thrombus and to minimize distal emboli.The system offers the user a degree of blood flow control so as toaddress the specific hemodynamic requirements of the cerebralvasculature. The system may include a flow controller, which allows theuser to control the timing and mode of aspiration.

In another aspect, there are disclosed methods and devices foradditionally providing flushing steps to minimize emboli entrapment inthe system and increased visibility of particulates in the system duringuse.

The following descriptions provide detailed implementations and benefitsof each aspect of the disclosed invention.

Referring again to FIG. 1 illustrating an implementation of an accesssheath 220. The sheath 220 can include a sheath body 222 that is theinsertable portion of the sheath 220 (i.e. the portion that inserts intothe patient), a proximal connector 226, an aspiration line 230, aproximal hemostasis valve 234 and a flush line 236. The sheath 220 mayalso include a proximal extension portion 240, and may also include avalve on the connector 226 to fluidly isolate the sheath body 222 fromthe proximal portion 240 of the access sheath 220. The access sheath 220may come in a kit with one or more dilators 250, and a sheath guidewire270.

The diameter of the sheath body 222 is suitable for insertion into thecarotid artery, with an inner lumen 223 that is suitably sized forproviding a passageway for catheters to treat the occlusion. In animplementation, the sheath body 222 can have an inner diameter of about0.074″ and an outer diameter of about 0.090″, corresponding to a 5French sheath size, an inner diameter of about 0.087″ and an outerdiameter of about 0.104″, corresponding to a 6 French sheath size, or aninner diameter of about 0.100″ and an outer diameter of about 0.177″,corresponding to a 7 French sheath size. The length of the sheath body222 is configured to enable the distal tip of the sheath body 222 to bepositioned as far distal as the petrous portion of the internal carotidartery. In an implementation, the sheath body 222 length is suitable fora transfemoral approach, in the range 80 to 90 cm or up to about 100 cmor up to about 105 cm. In an implementation, the sheath body 222 lengthis suitable for a transcarotid approach to the petrous ICA, in the range20 to 25 cm. In an implementation, the sheath body 222 length issuitable for a transcarotid approach to the CCA or proximal ICA, in therange 10-15 cm. The sheath body 222 is configured to assume and navigatethe bends of the vasculature and be subject to high aspiration forceswithout kinking, collapsing, or causing vascular trauma.

The sheath body 222 can be constructed in two or more layers. An innerliner can be constructed from a low friction polymer such as PTFE(polytetrafluoroethylene) or FEP (fluorinated ethylene propylene) toprovide a smooth surface for the advancement of devices through theinner lumen. An outer jacket material can provide mechanical integrityto the inner liner and may be constructed from materials such as PEBAX,thermoplastic polyurethane, polyethylene, nylon, or the like. A thirdlayer can be incorporated that can provide reinforcement between theinner liner and the outer jacket. The reinforcement layer can preventflattening or kinking of the inner lumen of the sheath body 222 to allowunimpeded device navigation through bends in the vasculature as well asaspiration or reverse flow. The sheath body 222 can be circumferentiallyreinforced. The reinforcement layer can be made from metal such asstainless steel, Nitinol, Nitinol braid, helical ribbon, helical wire,cut stainless steel, or the like, or stiff polymer such as PEEK. Thereinforcement layer can be a structure such as a coil or braid, ortubing that has been laser-cut or machine-cut so as to be flexible. Inanother implementation, the reinforcement layer can be a cut hypotubesuch as a Nitinol hypotube or cut rigid polymer, or the like.

The flexibility of the sheath body 222 can vary over its length, withincreasing flexibility towards the distal portion of the sheath body222. The variability in flexibility may be achieved in various ways. Forexample, the outer jacket may change in durometer and/or material atvarious sections. A lower durometer outer jacket material can be used ina distal section of the sheath compared to other sections of the sheath.Alternately, the wall thickness of the jacket material may be reduced,and/or the density of the reinforcement layer may be varied to increasethe flexibility. For example, the pitch of the coil or braid may bestretched out, or the cut pattern in the tubing may be varied to be moreflexible. Alternately, the reinforcement structure or the materials maychange over the length of the sheath body 222. In an implementation, thedistal-most section has a flexural stiffness (E*I) in the range 50 to300 N-mm2 and the remaining portion of the sheath body 222 has aflexural stiffness in the range 500 to 1500 N-mm2, where E is theelastic modulus and I is the area moment of inertia of the device. Inanother implementation, there is a transition section between thedistal-most flexible section and the proximal section, with one or moresections of varying flexibilities between the distal-most section andthe remainder of the sheath body 222. In this implementation, thedistal-most section is about 2 cm to about 5 cm, the transition sectionis about 2 cm to about 10 cm and the proximal section takes up theremainder of the sheath length.

The tip of the sheath body 222 may include one or more distal radiopaquemarkers 224 (see FIG. 1 ). In an implementation, the radiopaque tipmarker 224 is a metal band, for example platinum iridium alloy, embeddednear the distal end of the sheath body 222. Alternately, the accesssheath tip material may be a separate radiopaque material, for example abarium polymer or tungsten polymer blend. The distal region of thesheath body 222 is also the area of the overlap region 120 that allows aseal between the catheter 320 and the sheath body 222, creating acontinuous aspiration lumen. Thus, the outer diameter of the luminalportion 322 of the aspiration catheter 320 approaches the inner diameterof the distal region of the sheath body 222 lumen 223 such that a sealis formed. The relative location of the seal formed may vary dependingon where the aspiration catheter 320 exits the lumen 223 of the sheathbody 222 and the location of the openings from the sheath body 222, asdescribed in more detail below. For example, if the sheath body 222 hasan opening at the distal tip the location of the seal may be closer tothe distal end of the sheath body 222 compared to if the sheath body 222has one or more side openings in the distal end region of the sheathbody 222 through which the catheter 320 exits the lumen 223.

Referring again to FIG. 1 , the access sheath 220 also can include aconnector 226 that connects a proximal end of the sheath body 222 to theproximal hemostasis valve 234, and also provides a connection to theaspiration line 230. This connector 226 can have a large bore innerlumen, and connects to a large-bore aspiration line 230. In animplementation, the inner lumen of the connector 226 is at least 0.080″.In an implementation, the inner lumen of the aspiration line 230 is atleast 0.080″. The aspiration line 230 can terminate in a stopcock,female Luer connector, or other connector 232 that allows connection toan aspiration source. In an implementation, the aspiration source is anactive aspiration source such as a syringe or a pump. In anotherimplementation, the aspiration source is a reverse flow shunt line suchas that described in U.S. Pat. No. 8,157,760 and US Patent PublicationNumber 2010/0217276, which are both incorporated by reference. The largebore aspiration line 230 can be constructed to be resistant to collapse.For example, the aspiration line 230 can be a thick-walled polymertubing or a reinforced polymer tubing. The aspiration line valve 232enables the line 230 to be opened or closed. In one implementation, thevalve 232 also allows connection of one or more additional fluid lines,for connecting a forward drip or a flush line for contrast or salineinjections. As an example, the valve 232 may be a stopcock manifoldcommonly used in interventional procedures to allow multipleconnections. The connector 226 may also include means to secure theaccess sheath 220 to the patient to reduce the risk of sheathdislodgement during the case. For example, the connector 226 may includeone or more suture eyelets 233.

With reference still to FIG. 1 , the proximal end of the access sheath220 can terminate in a proximal hemostasis valve 234. This valve 234allows the introduction of devices through the sheath 220 into thevasculature, while preventing or minimizing blood loss and preventingair introduction into the access sheath 220. The hemostasis valve 234can include a flush line 236 or a connection to a flush line 236 so thatthe sheath 220 can be flushed with saline or radiopaque contrast duringthe procedure as desired. The flush line 236 can also be used as asecond point of aspiration during portions of the procedure as describedmore fully below. The hemostasis valve 234 can be a static seal-typepassive valve, or an adjustable-opening valve such as a Tuohy-Borstvalve or rotating hemostasis valve (RHV). The hemostasis valve 234 canbe integral to the access sheath 220, or the access sheath 220 canterminate on the proximal end in a female Luer adaptor to which aseparate hemostasis valve 234 component, such as a passive seal valve, aTuohy-Borst valve or rotating hemostasis valve may be attached. In animplementation, the valve 234 has an adjustable opening that is openlarge enough to allow removal of devices that have adherent clot on thetip without causing the clot to dislodge at the valve 234 duringremoval. Alternately, the valve 234 is removable and is removed when thecatheter tip is being removed from the sheath 220 to prevent clotdislodgement at the valve 234.

Referring again to FIG. 1 , the arterial sheath system 200 can includeone or more sheath dilators 250 and a sheath guidewire 270. The sheathguidewire 270 can be inserted first into the artery using standardvascular access techniques such as a micropuncture technique or ModifiedSeldinger technique. The sheath dilator 250 allows for smooth insertionof the access sheath 220 through a puncture site in the arterial wall.The dilator 250 can be inserted into the access sheath 220 and then thetwo components can be inserted together over the sheath guidewire 270into the artery. The distal end 256 of the dilator 250 can be generallytapered to allow the dilator 250 to dilate the needle puncture site asit is being inserted through the arterial wall into the artery. Thetapered distal end 256 can be generally between 6 and 12 degrees totalincluded angle (relative to a longitudinal axis of the dilator), with aradiused leading edge.

An inner lumen of the dilator 250 can accommodate the sheath guidewire270, and can have an inner diameter of between 0.037″ to 0.041″ tocorrespond to a sheath guidewire 270 of between 0.035″ to 0.038″.Alternately, the inner lumen of the dilator 250 can be between 0.020″ to0.022″ to accommodate a sheath guidewire 270 of between 0.014″ to0.018″. Alternately, the dilator 250 can be a two part dilator with aninner dilator and an outer dilator. The outer dilator can have an innerdiameter of between 0.037″ to 0.041″, and the inner dilator can have aninner diameter of between 0.020″ to 0.022″. In use, the sheath 220 canbe inserted into the artery with the outer dilator with a sheathguidewire 270 between 0.035″ and 0.038″. The sheath guidewire 270 maythen be removed and replaced with the inner dilator and a smallerguidewire of between 0.014″ and 0.018″, and the access sheath 220 canthen be advanced further distally to the desired site in the carotidartery.

To insert the arterial sheath 220 initially over the sheath guidewire270 into the artery, the dilator taper 256 can have a certain stiffnessand taper angle to provide the adequate dilating force on the arterialpuncture site. However, to safely reach the petrous portion of the ICA,it may be desirable to have a sheath dilator 250 with a softer and/orlonger taper at a distal end than that used for initial arterial access.In an implementation, the access sheath system 200 can include two ormore tapered dilators. The first tapered dilator can be used with thearterial access device to gain entry into the artery, and is thus sizedand constructed in a manner similar to standard introducer sheathdilators. Example materials that may be used for the tapered dilatorinclude, for example, high density polyethylene, 72D PEBAX, 90D PEBAX,or equivalent stiffness and lubricity material. A second tapered dilatormay be supplied with a softer distal section or a distal section thathas a lower bending stiffness relative to the distal section of thefirst tapered dilator, and/or a longer taper length. That is, the seconddilator has a distal region that is softer, more flexible, orarticulates or bends more easily than a corresponding distal region ofthe first dilator. The distal region of the second dilator thus bendsmore easily than the corresponding distal region of the first dilator.In an implementation, the distal section of the first dilator has abending stiffness in the range of 50 to 100 N-mm2 and the distal sectionof the second dilator has a bending stiffness in the range of 5 to 15N-mm2. The second dilator (which has a distal section with a lowerbending stiffness) may be exchanged with the initial, first dilator suchthat the access sheath 220 may be advanced into the internal carotidartery and around curvature in the artery without undue force or traumaon the vessel due to the softer distal section of the second dilator.

The distal section of the soft, second dilator may be, for example, 35or 40D PEBAX, with a proximal portion made of, for example 72D PEBAX. Anintermediate mid portion or portions may be included on the seconddilator to provide a smooth transition between the soft distal sectionand the stiffer proximal section. In an implementation, both dilatorshave an inner diameter of between 0.037″ to 0.041″. In an alternateimplementation, the first dilator has an inner diameter of between0.037″ to 0.041″ and the second dilator has an inner diameter of between0.020″ to 0.022″. In yet another implementation, the second dilator is atwo part dilator with an inner dilator and an outer dilator, asdescribed above. In an implementation, one or both dilators may haveradiopaque tip markers 224 so that the dilator tip position is visibleon fluoroscopy. In one variation, the radiopaque marker 224 is a sectionof tungsten loaded PEBAX or polyurethane that is heat welded to thedistal tip of the dilator. Other radiopaque materials may similarly beused to create a radiopaque marker 224 at the distal tip.

In an implementation, the access sheath 220 includes a proximalextension 240 that extends between the connector 226 and the proximalhemostasis valve 234. In the transcarotid configuration of the system,it may be desirable to move the proximal hemostasis valve 234 away fromthe distal tip of the access sheath 220, effectively elongating orlengthening the proximal portion of the access sheath that is outsidethe body while maintaining the length of the insertable sheath bodyportion 222. This allows the user to insert devices into the proximalhemostasis valve 234 of the access sheath 220 from a point further awayfrom the target site and therefore away from the x-ray source and/orimage intensifier used to image the target site fluoroscopically,thereby minimizing radiation exposure of the user's hands and also hisor her entire body. In this implementation, the proximal extension 240can be in the range between 10 and 25 cm, or between 15 and 20 cm. Ineither the transcarotid or transfemoral configuration, it may also bedesirable to provide a section of the access sheath 220 that is fluidlyconnected to the access sheath aspiration line, but which may extendproximally from the aspiration line connection. This will allow users topull devices out of the flow of blood from the sheath tip to theaspiration line, without completely removing the device from the accesssheath 220.

In an alternate implementation, it may also be desirable tointermittently isolate this proximal portion 240 from the sheath body222. In an implementation, as shown in FIG. 4 , the connector 226includes a valve 242 that can close off the fluid connection between thesheath body 222 and the proximal portion 240 of the access sheath 220,including the aspiration line 230, proximal extension 240 and proximalhemostasis valve 234. This can allow the distal portion of a catheter,retrievable stent device, or other thrombectomy device to be pulled intothis proximal extension portion 240, the valve 242 closed to fluidlyisolate the sheath body 222 from the proximal portion of the sheath, andthen the proximal hemostasis valve 234 to be widely opened or removed,or the entire proximal extension portion 240 of the sheath 220 removed,without arterial bleeding from the sheath 220. The proximal extension240 can be at least as long as the distal luminal portion 222 of thespined catheter 320 so that the distal luminal portion 322 may be pulledentirely into the proximal extension 240 and the valve 242 closed offbefore the proximal hemostasis valve 234 is widely opened to remove thecatheter 320 entirely from the sheath 220.

Alternately, after the thrombectomy device or other interventionaldevice is pulled into this proximal extension portion 240 and the sheathbody 222 closed off via the valve 242, a portion of the thrombectomydevice, such as the distal luminal portion 322 of the aspirationcatheter 320, may remain in the proximal extension 240 and be flushed orotherwise cleared by creating flow from the flush line to the aspirationlines to dislodge clot without fully removing the device 320 from theaccess sheath 220. This ability to flush and clear the thrombectomydevice without fully removing the thrombectomy device may reducebleeding, time, and risk of air emboli during the steps betweenthrombectomy attempts. Also, withdrawing the thrombectomy device intothe proximal extension 240 without fully removing it from the sheathbody 222 while flushing and clearing also minimizes operator and staffexposure to blood and debris associated with device cleansing. In any ofthese implementations, the proximal extension tubing is clear so thatthe flush solution and presence/absence of embolic debris or air isclearly visible through the tubing.

The proximal extension portion 240 of the access sheath 220 can beprovided as a separate, removable component that can be attached to anysheath with a standard connection on the proximal end. As shown in FIG.5 , a proximal component 280 includes a connector 285 that can attach toa proximal hub 15 of a standard sheath 10. The coupled components cancreate an assembly with the configuration and features of access sheath220. In this implementation, the user can select from any of severalalready available sheaths of appropriate length, shape, and mechanicalcharacteristics for the procedure, and perform the steps of theprocedure described in this disclosure. The removable proximal component280 can include the Y-arm connector 226, aspiration line 230, proximalextension 240, proximal hemostasis valve 234 and flush line 236, alongwith the valve connectors 232 and 238 terminating the aspiration line230 and flush line 236 respectively. A connector 285 can couple to theproximal connector 226 on the sheath 220. In an implementation as shownin FIG. 6 , the connector 285 is configured to minimize the flowresistance through the sheath 10 and into the proximal portion 280. Forexample, instead of a standard male-female Luer connection, theconnector 285 can include an adaptor 60 with an inner lumen and surfacethat matches a standard female Luer connector 62 typically found onsheaths, a seal element 64 that seals between the adaptor 60 and thesheath female Luer 62, and a rotating nut 66 that engages the threadelements of the female Luer 62 and couples the adaptor 60 and Luer 62together such that the seal 64 is compressed and can seal against fluidand air vacuum and pressure. Again with respect to FIG. 5 , the proximalcomponent 280 may also include a valve 242 on the Y-arm connector 226,so that when the proximal component 280 is attached to a sheath 10, theproximal section may be selectively open or closed to fluid connectionwith the sheath 10. A similar type of connection can be made forconnector 232 connecting the sheath aspiration line 230 to an aspirationsource.

In a preferred implementation, the proximal connection has a proximalextension length of about 22 cm, a Y-arm connector of about 7 cm, and aproximal hemostasis valve of length about 5 cm for a total length ofabout 34 cm.

It may be desirable to transiently occlude the carotid artery during theintervention to arrest antegrade flow of emboli during portions of theprocedure. In an implementation, as shown in FIG. 7 , the access sheath220 includes an occlusion balloon 246 on the distal tip of the sheathbody 222. An additional lumen in sheath body 222 can be connected to aninflation line 248 and fluidly connects the balloon 246 to the inflationline 248. An inflation device is attached to inflation line 248 toinflate the occlusion balloon 246. In this implementation, the balloon246 is inflated when carotid artery occlusion is desired.

In some instances it is desirable to keep the sheath tip as small aspossible during sheath insertion to minimize the diameter of thearterial puncture, but to expand the opening of the sheath 220 after ithas been inserted into the vessel. At least one purpose of this featureis to minimize the effect or creation of distal emboli during pull backof an aspiration catheter 320 or other thrombectomy device into thesheath 220. During a thrombectomy procedure, the thrombus may be “pulledback” into a distal opening 221 of the sheath 220 on a device that hascaptured the thrombus. If the distal tip of the sheath 220 is enlargedrelative to its initial size, or flared into a funnel shape, the chanceof pieces of the thrombus breaking off and causing emboli is minimizedbecause the larger size or funnel shape of the sheath tip is more likelyto accommodate the emboli being drawn into it without being split intomultiple pieces. This creates a better clinical outcome for the patient.In an implementation of the access sheath, the distal portion of thesheath body 222 is a material and/or construction such that the tip canbe expanded after the sheath 220 is inserted into the artery andpositioned in its desired location. In an implementation, the distalregion of the sheath has an ID of about 0.087″ can be enlarged to adiameter of about 0.100″ to 0.120″ although the size may vary and/or beflared.

Examples of expanding distal tip constructions include covered braidedtips that can be shortened to expand. Another example of an expandingdistal tip construction is an umbrella or similar construction that canopen up with mechanical actuation or elastic spring force whenunconstrained. Other mechanisms of expandable diameter tubes are wellknown in the art. One particular implementation is a sheath made ofmaterial that is deformable when expanded using a high pressure balloon.Co-pending U.S. Patent Publication number 2015/0173782, filed on Dec.19, 2014, describes exemplary devices and is incorporated herein byreference in its entirety. Construction of such features are describedin co-pending Publication number 2015/0173782.

The distal end region of the sheath body 222 also may vary in thelocation, size and number of openings. The sheath body 222 mayincorporate one or more openings near the distal end region of thesheath 220 that allow for fluid flow between the lumen 223 of the sheathbody 222 and the vasculature within which the sheath 220 is positioned.The one or more openings can be sized to allow at least the luminalportion 322 of the aspiration catheter 320 to extend therethrough. Theone or more openings may be sized larger than the outer diameter of theluminal portion 322 such that the one or more openings form an elongatemouth, slot or notch in a distal end region of the sheath body 222. Theone or more openings may be formed within a region of the side wall ofthe sheath body 222 just proximal to the distal end, such that theopening is located at least 0.25 mm, 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5mm, 3.0 mm, 3.5 mm, or 4.0 mm or greater from the distal end of thesheath body 222. The one or more openings may be a plurality of openingsforming a porous region near the distal end region of the sheath body222 wherein at least one of the pluralities of openings is sized largeenough to allow one or more components of the system to exit the lumen223 of the sheath body 222. In some implementations, the one or moreopenings includes a distal opening 221 from the lumen 223 of the sheathbody 222 (see FIGS. 4 and 12C). In some implementations, the one or moreopenings includes an elongate, distal mouth forming a side opening 1219on a first side of the sheath body 222 located near a distal end region(see FIG. 12C). The side opening 1219 may be located at least 0.25 mm ormore from the distal end of the sheath body 222. The side opening 1219may having a diameter that is at least as large as the outer diameter ofthe distal luminal portion 322 of the spined catheter 320. Preferably,the side opening 1219 has a diameter that is at least 1.5×, 2×, 2.5×, or3× as large as the outer diameter of the distal luminal portion 322. Inanother implementation, the sheath body 222 includes a pair of sideopenings 1219 on opposing and/or adjacent sides of the sheath body 222near the distal end region. In another implementation, the sheath body222 includes a distal opening 221 from the lumen 223 and one or moreelongate side openings 1219 from the lumen 223. It should be appreciatedthat the sheath body 222 can be rotated around the longitudinal axis Asuch that the one or more side openings 1219 are positioned to allow fordistal extension of the catheter 320 from the side openings 1219 in adesired direction relative to the longitudinal axis A of the sheath 220.Inclusion of a wide-mouthed side opening 1219 can allow for a range ofexit angles for the catheter 320 from a position substantially (i.e.very nearly) parallel to the sheath body 222 to a position that is at anangle to the sheath body 222, for example substantially perpendicular orat a right angle to the sheath body 222, as well as greater than 90°angle. This arrangement can be critically important in situations wherethere is severe angulation within the vessel being traversed or where abifurcation is present. Often, tortuous segments in vessels andbifurcations have severe angulations to 90° or greater angle up to 180°.Classic severe angulation points in the vasculature can include theaorto-iliac junction, the left subclavian artery takeoff from the aorta,the brachiocephalic (innominate) artery takeoff from the ascending aortaas well as many other peripheral locations.

Referring again to FIG. 1 , as mentioned above the catheter system 300can include a spined aspiration catheter 320 having a flexible, distalluminal portion 322 and a rigid, proximal spine 330. The outer diameterof the distal luminal portion 322 as well as the flexibility andlubricity of the luminal portion 322 paired with the rigid spine 330allow for the spined aspiration catheter 320 to navigate to the site ofocclusions in the cerebral vasculature compared to other systemsconfigured to navigate the cardiac vasculature. The systems describedherein can reach occlusions in a region of the anatomy that has a long,tortuous access route. The route may contain stenosis plaque material inthe aortic arch and carotid and brachiocephalic vessel origins,presenting a risk of embolic complications. Further, cerebral vesselsare usually more delicate and prone to perforation than coronary orother peripheral vasculature. The catheter systems described herein canprovide for neurovascular interventional procedures more easily due toits ability to overcome these access challenges. The catheter systemsdescribed herein are designed for navigating tortuosity rather thanpushing through it. U.S. Patent Publication Number 2015/0174368, filedon Dec. 12, 2014, and U.S. Patent Publication Number 2015/0173782, filedon Dec. 19, 2014, which are incorporated herein by reference, describefeatures of catheter devices that can navigate the tortuous anatomy ofthe cerebral arteries.

The length of the distal luminal portion 322 can vary. In someimplementations, the length of the distal luminal portion 322 extendsfrom a region near the distal tip of the access sheath body 222 to thesite of the occlusion in the carotid artery, forming a proximal overlapregion 120 with the distal end of the access sheath 220 (see FIG. 2B).Taking into account the variation in occlusion sites and sites where theaccess sheath distal tip may be positioned, the length of the distalluminal portion 322 may range from about 10 cm to about 25 cm. Thelength of the distal luminal portion 322 is less than the length of thesheath body 222 of the access sheath 220, such that as the spinedaspiration catheter 320 is retracted into the sheath body 222 thereremains a seal between the overlap region 328 of the spined aspirationcatheter 320, and the inner diameter of the sheath body 222.

The catheter systems described herein can incorporate multiple spinedcatheters that are nested inside one another to allow for an extendedreach into the tortuous anatomy. For example, a first spined catheter320 having an outer diameter sized to be received within the lumen ofthe sheath body 222 may have a second spined catheter 320 extendingthrough the inner lumen of the first spined catheter 320. The secondspined catheter 320 can be extended using its proximal spine beyond adistal end of the first spined catheter 320 such that the smallerdiameter second spined catheter 320 can reach a more distal region ofthe vasculature, particularly one having a narrower dimension. In thisimplementation, the first spined catheter 320 can act as a supportcatheter for the second spined catheter 320. The second spined catheter320 can have an inner lumen that fluidly communicates with the innerlumen of the first spined catheter 320 that fluidly communicates with aninner lumen of the sheath body 222 forming a contiguous aspirationlumen.

In an implementation, the distal luminal portion 322 of the catheter 320is constructed to be flexible and lubricious, so as to be able to besafely navigated to the target site, and kink resistant and collapseresistant when subjected to high aspiration forces, so as to be able toeffectively aspirate the clot, with sections of increasing flexibilitytowards the distal end. In an implementation, the distal luminal portion322 includes three or more layers, including an inner lubricious liner,a reinforcement layer, and an outer jacket layer. The outer jacket layermay be composed of discreet sections of polymer with differentdurometers, composition, and/or thickness to vary the flexibility alongthe length of the distal luminal portion 322. In an implementation thelubricious inner liner is a PTFE liner, with one or more thicknessesalong variable sections of flexibility. In an implementation, thereinforcement layer is a generally tubular structure formed of, forexample, a wound ribbon or wire coil or braid. The material for thereinforcement structure may be stainless steel, for example 304stainless steel, nitinol, cobalt chromium alloy, or other metal alloythat provides the desired combination of strengths, flexibility, andresistance to crush. In an implementation, the reinforcement structureincludes multiple materials and/or designs, again to vary theflexibility along the length of the distal luminal portion 322. In animplementation, the outer surface of the catheter 320 is coated with alubricious coating such as a hydrophilic coating. In someimplementations the coating may be on an inner surface and/or an outersurface to reduce friction during tracking. The coating may include avariety of materials as is known in the art. The spine portion 330 mayalso be coated to improve tracking through the access sheath 220.Suitable lubricious polymers are well known in the art and may includesilicone and the like, hydrophilic polymers such as high-densitypolyethylene (HDPE), polytetrafluoroethylene (PTFE), polyarylene oxides,polyvinylpyrolidones, polyvinylalcohols, hydroxy alkyl cellulosics,algins, saccharides, caprolactones, and the like, and mixtures andcombinations thereof. Hydrophilic polymers may be blended amongthemselves or with formulated amounts of water insoluble compounds(including some polymers) to yield coatings with suitable lubricity,bonding, and solubility.

The outer diameter of the distal luminal portion 322 can be sized fornavigation into cerebral arteries. It is desirable to have a catheterhaving an inner diameter that is as large as possible that can benavigated safely to the site of the occlusion, in order to optimize theaspiration force. A suitable size for the inner diameter may rangebetween 0.040″ and 0.075″ or may range between 0.040″ and 0.088″,depending on the patient anatomy and the clot size and composition. Theouter diameter should be as small as possible while still maintainingthe mechanical integrity of the catheter 320. However, at the overlapregion 120, the outer diameter (OD) of the catheter 320 approaches theinner diameter (ID) of the access sheath 220, so as to create a sealedarea at the overlap region 120 whilst still enabling the catheter 320 tobe inserted easily through the sheath 220 and positioned at the desiredsite. In an implementation, the catheter 320 and access sheath 220 aresized to match at the overlap region 120 with no change in catheter 320outer diameter (see FIG. 2B). In an implementation, the differencebetween the catheter OD and the access sheath ID at the overlap regionis 0.002″ or less. In another implementation, the difference is 0.003″or less. In an implementation, the catheter 320 is tapered towards thedistal tip of the distal luminal portion 322 such that the distal-mostend of the catheter has a smaller outer diameter compared to a moreproximal region of the catheter near where it seals with the accesssheath. In another implementation, the catheter OD steps up at anoverlap portion 328 to more closely match the sheath inner diameter (seeFIG. 1 ). This implementation is especially useful in a system with morethan one catheter suitable for use with a single access sheath size. Itshould be appreciated where the catheter OD of the spined catheter 320matches the sheath inner diameter or the difference is 0.002″ or less, aseal to fluid being injected or aspirated can be achieved by the overlapportion 328 such that no increase in catheter OD is necessary. A seal tofluid being injected or aspirated between the catheter and the sheathcan be achieved by the overlap between their substantially similardimensions without incorporating any separate sealing structure or sealfeature.

In another implementation as shown in FIGS. 8A and 8B, there is asealing element 336 positioned on the external surface of the proximalend of the distal luminal portion 322. The sealing element 336 can beone or more external ridge features, and can be compressed when thecatheter 320 is inserted into the lumen of the access sheath 220. Theridge geometry can be such that the sealing element 336 behaves as anO-ring, quad ring, or other piston seal design. FIG. 8B shows a similarconfiguration, with the sealing element 336 having a wiper sealconfiguration such as an inclined surface that is biased against aninner surface of access sheath body 222. Alternately, the seal element336 may be an inflatable or expandable member such as a balloon orcovered braid structure that can be inflated or expanded and providesealing between the two devices at any time, including after thecatheter 320 is positioned at the desired site. An advantage to thisimplementation is that there is no sealing force being exerted on thecatheter 320 during catheter positioning, but rather is applied oractuated to seal after the catheter 320 is positioned.

It should be appreciated that the shape of the proximal end region ofthe distal luminal portion 322 may have an angled cut compared to thestraight cut shown in the FIGS. 8A-8B. It should also be appreciatedthat the spine 330 may be coupled to a proximal end region of thecatheter 320 and/or may extend along at least a portion of the distalluminal portion 322 such that the spine 330 couples to the distalluminal portion 322 a distance away from the proximal end. The spine 330can be coupled to the portion 322 by a variety of mechanisms includingbonding, welding, gluing, sandwiching, stringing, tethering, or tyingone or more components making up the spine 330 and/or portion 322. Insome implementations, the spine 330 and luminal portion 322 are coupledtogether by sandwiching the spine 330 between layers of the distalluminal portion 322. For example, the spine 330 can be a hypotube or rodhaving a distal end that is skived, ground or cut such that the distalend can be laminated or otherwise attached to the layers of the catheterportion 322 near a proximal end region. The region of overlap betweenthe distal end of the spine 330 and the portion 322 can be at leastabout 1 cm. This type of coupling allows for a smooth and eventransition from the spine 330 to the luminal portion 322.

In an implementation, the overlap region is configured to enable sealingagainst a vacuum of up to 25 inHg, or up to 28 inHg. In animplementation, the overlap region 120 is configured to enable sealingagainst a pressure of up to 300 mmHg or up to 600 mmHg or up to 700 mmHgwith minimal to no leakage. In addition, there may be features thatprevent excessive advancement of the spined aspiration catheter 320beyond the distal end of the access sheath 220. In any implementationthat involves a stepped up diameter or protruding feature at the overlapregion 328 of the spined aspiration catheter 320, the access sheath body222 may include an undercut at the tip that prevents the proximaloverlap portion of the spined aspiration catheter 320 to exit the sheathbody 222.

The distal luminal portion 322 of the catheter 320 can have a radiopaquemarker 324 at the distal tip to aid in navigation and proper positioningof the tip under fluoroscopy (see FIG. 1 ). Additionally, the proximaloverlap region 328 of the catheter 320 may have one or more proximalradiopaque markers 1324 (see FIG. 12C) so that the overlap region 120can be visualized as the relationship between the access sheath distalmarker 224 and the catheter proximal marker 1324. In an implementation,the two markers (marker 324 at distal tip and a more proximal marker1324) are distinct so as to minimize confusion of the fluoroscopicimage, for example the catheter proximal marker 1324 may be a singleband and the sheath tip marker 224 may be a double band.

The spine 330 of the spined aspiration catheter 320 is coupled to aproximal end region of the distal luminal portion 322. The spine 330 isconfigured to allow distal advancement and proximal retraction of thecatheter 320 through the lumen 223 of the access sheath 220. In animplementation, the length of the spine 330 is longer than the entirelength of the access sheath 220 (from distal tip to proximal valve),such as by about 5 cm to 15 cm. As shown in FIG. 1 , the spine 330 caninclude a mark 332 to indicate the overlap between the distal luminalportion 322 of the catheter 320 and the sheath body 222. The mark 332can be positioned so that when the mark 332 is aligned with the sheathproximal valve 234 during insertion of the catheter 320 through thesheath 220, the spined aspiration catheter 320 is positioned at thedistal-most position with the minimal overlap length needed to createthe seal between the spined aspiration catheter 320 and the accesssheath 220. The spine 330 can include a gripping feature such as a tab334 on the proximal end to make the spine easy to grasp and advance orretract. The tab 334 can coupled with one or more other components ofthe system 300, such as a dilator configured to extend through the lumen323 of the distal luminal portion 322 as will be described in moredetail below. The proximal tab 334 can be designed to be easilyidentifiable amongst the other devices existing in the sheath proximalvalve 234, such as guidewires 270 or retrievable stent device wires 500.In an implementation, the spine 330 is colored a bright color, or markedwith a bright color, to make it easily distinguishable from guidewire,retrievable stent tethers, or the like.

The spine 330 can be configured with sufficient stiffness to allowadvancement and retraction of the distal luminal portion 322 of thespined aspiration catheter 320, yet also be flexible enough to navigatethrough the cerebral anatomy as needed. Further, the outer diameter ofthe spine 330 is sized to avoid taking up too much luminal area in thelumen 223 of the access sheath 220 and sheath body 222. In animplementation, the spine 330 is a round wire, with dimensions from0.014″ to 0.018″. In another implementation, the spine 330 is a ribbonwith dimensions ranging from 0.010″ to 0.015″ thick, and 0.015″ thick to0.025″ thick. The ribbon can have a variety of cross-sectional shapessuch as a flat ribbon or curved ribbon forming a c-shape or other shapealong an arc. In another implementation, the spine 330 is a hypotube. Inan implementation, the spine 330 material is a metal such as a stainlesssteel or nitinol as well as a plastic such as any of a variety ofpolymers.

One or more components of the systems described herein may be made froma metal, metal alloy, polymer, a metal-polymer composite, ceramics,combinations thereof, and the like, or other suitable materials. Someexamples of suitable metals and metal alloys include stainless steel,such as 304V, 304L, and 316LV stainless steel; mild steel;nickel-titanium alloy such as linear-elastic and/or super-elasticnitinol; other nickel alloys such as nickel-chromium-molybdenum alloys(e.g., UNS: N06625 such as INCONEL® 625, UNS: N06022 such as HASTELLOY®C-22®, UNS: N10276 such as HASTELLOY® C276®, other HASTELLOY® alloys,and the like), nickel-copper alloys (e.g., UNS: N04400 such as MONEL®400, NICKELVAC® 400, NICORROS® 400, and the like),nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such asMP35-N® and the like), nickel-molybdenum alloys (e.g., UNS: N10665 suchas HASTELLOY® ALLOY B2®), other nickel-chromium alloys, othernickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-ironalloys, other nickel-copper alloys, other nickel-tungsten or tungstenalloys, and the like; cobalt-chromium alloys; cobalt-chromium-molybdenumalloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like);platinum enriched stainless steel; titanium; combinations thereof; andthe like; or any other suitable material.

The junction between the distal luminal portion 322 of the catheter 320and the proximal spine 330 can be configured to allow a smoothtransition of flexibility between the two portions so as not to create akink or weak point, and also allow smooth passage of devices such asguidewires and microcatheters through the continuous inner lumen createdby the lumen 223 of the access sheath 220 and the lumen 323 of theluminal portion 322 of the catheter 320. In an implementation, thedistal luminal portion 322 has a transition section 326 (see FIG. 1 )near where the portion 322 couples to the spine 330 that has an angledcut such that there is no abrupt step transition from the sheath 220inner lumen 223 to the catheter 320 inner lumen 323. The angled cut canbe generally planer. In an alternate implementation, the angled cut iscurved or stepped to provide a more gradual transition zone. The distalluminal portion 322 and the spine 330 may be joined by a weld bond, amechanical bond, an adhesive bond, or some combination thereof. Thedistal end of the spine 330 may have features that facilitate amechanical joint during a weld, such as a textured surface, protrudingfeatures, or cut-out features. During a heat weld process, the featureswould facilitate a mechanical bond between the polymer distal luminalportion 322 and the spine 330. In another implementation, such as thecatheter system 1300 shown in FIGS. 12A-12B having a spined catheter1320 and a dilator 1340 extending therethrough, a smooth transition offlexibility between the two portions is formed so as not to kink orcreate a weak point during advancement of the system 1300. Loss of thissmooth flexibility transition can occur upon removal of the dilator 1340from the spined catheter 1320. The spine 1330 can be intended primarilyto withdraw the spined catheter 1320 where risk of kink or weak spotformation is markedly lower.

Because the spined aspiration catheter 320 does not have a lumen thatruns its entire length 320 due to the presence of the spine 330 on itsproximal end region, traditional flushing and preparation steps, eitherbefore use or during the procedure should the lumen of the catheterbecome clogged, are ineffective. In a traditional single lumen catheter,a syringe is attached to the proximal adaptor of the catheter and theinner lumen may be forcefully flushed with solution. The spined catheter320 can be supplied with an accessory catheter flushing and clearingdevice 350 (see FIG. 1 ). This device 350 may be a tube with a roundedor tapered tip on a distal end and a female Luer connection on theproximal end. The Luer connector allows a syringe to be connected to thedevice 350. The blunt or tapered tip enables the device 350 to beinserted into either the distal or proximal end of the luminal portion322 of the catheter 320, without risk of damaging the catheter 320, andthe syringe actuated to flush the device. The OD of the clearing device350 is closely matched with the ID of the luminal portion 322 of thespined catheter 320, such that the spined aspiration catheter 320 may beflushed with enough force to clear out the catheter of debris andaspirated occlusive material. The device 350 may also be used tomechanically clear out any entrapped thrombus in a plunger-type action,the working length of the device 350 can be at least as long as thedistal luminal portion 322 of the catheter 320, so that it may beinserted through the entire lumen 323 of the distal luminal portion 322.Flushing may occur in conjunction with plunging the device 350, to moreeffectively clear the catheter 320 of entrapped thrombus or otherembolic material.

In an alternate implementation, the aspiration catheter 320 is a singlelumen catheter, for example, the type of catheter described inco-pending application U.S. Patent Publication Number 2015/0174368,filed Dec. 12, 2014. In such an implementation, the catheter may besupplied with or coupled with a tapered co-axial dilator 340 that isgenerally tubular and has a tapered distal portion that provides asmooth transition between the catheter and a guidewire positioned withinthe catheter.

The spined aspiration catheter 320 can be navigated through thevasculature over an appropriately-sized microcatheter and guidewire.Alternately, the spined catheter 320 can be supplied with a co-axialdilator 340 (see FIG. 1 ). The dilator 340 is sized and shaped to beinserted through the internal lumen 323 of the distal luminal portion322 of the catheter 320 in a coaxial fashion, such that a proximal endregion of the dilator 340 aligns side-by-side with the spine 330 of thecatheter 320 when in use. The dilator 340 can have a tapered distal tip346. The length of the dilator 340 can be at least as long as the spinedaspiration catheter 320 allowing for the distal tapered tip 346 as aminimum to protrude from the distal end of the luminal portion 322 ofthe spined catheter 320. The dilator 340 can have an outer diameter thatforms a smooth transition to the distal tip of the catheter, and thedistal tapered tip 346 that provides a smooth transition down to theguidewire that extends out the inner lumen of the dilator 340. Thedilator 340 can be generally tubular along at least a portion of itslength. In an implementation, the tapered dilator 340 is designed toaccommodate a guidewire that may be in the range of 0.014″ and 0.018″diameter for example. In this implementation, the inner luminal diametermay be between 0.020″ and 0.024″. The tapered distal tip 346 may be inrange from 1.5 cm to 3 cm.

It should be appreciated that the dilators described herein for use withthe spined catheters can vary in their configuration. For example, asdescribed above the dilator 340 can be a co-axial dilator 340 that isgenerally tubular and has a tapered distal portion that provides asmooth transition between the catheter 320 and a guidewire positionedwithin the catheter 320. The tubular body of the dilator 340 can extendalong the entire length of the catheter 320. Alternatively, the dilator340 can incorporate a proximal spine that aligns side-by-side with thespine of the catheter 320. The proximal spine can be positioned co-axialor eccentric to a distal end region of the dilator 340. The co-axialproximal spine of the dilator 340 can have a lumen extending through it.Alternatively, the dilator 340 can be a solid rod having no lumen. Thesolid rod dilator can be formed of a malleable material that skives downto have a narrow outer diameter (e.g. 0.010″-0.014″) such that thedilator can be shaped to whatever angle or shape is desired by the user,similar to how a guidewire may be used. In this configuration, thecatheter system does not include a guidewire or microcatheter. Such adilator has a benefit over a microcatheter in that it can have an outerdiameter that is 0.003″-0.010″ smaller than the inner diameter of thespined catheter 320.

The dilator 340 may have a proximal female Luer adaptor 348 at aproximal end to allow the dilator 340 to be flushed with a syringe. Thedilator 340 may also incorporate a clip feature at a proximal endallowing the dilator 340 to be the material of the dilator 340 can beflexible enough and the taper distal tip 346 can be long enough tocreate a smooth transition between the flexibility of the guidewire andthe flexibility of the catheter. This configuration can facilitateadvancement of the catheter 320 through the curved anatomy and into thetarget cerebral vasculature. In an implementation, the distal end of thedilator 340 has a radiopaque marker 344 and/or a marker 343 at theproximal end of the taper distal tip 346. The marker material may be aplatinum/iridium band, a tungsten, platinum, or tantalum-impregnatedpolymer, or other radiopaque marker.

The dilator 340 can be constructed to have variable stiffness betweenthe distal and proximal ends of the dilator 340. For example, the distalmost section that extends beyond the distal end of the luminal portion322 of the catheter 320 can be made from a more flexible material, withincreasingly stiffer materials towards the more proximal sections. Insome implementations, the dilator 340 can be a spined dilator having aproximal spine as will be described in more detail below. The proximalend of the dilator 340 can include a tab 1364 that allows the dilator340 to lock with the tab 334 on the proximal end of the spine 330 of thecatheter 320, such that the two components (the spined catheter 320 andthe dilator 340) may be advanced as a single unit over the guidewire(see FIG. 12A). In some implementations, the tab 334 of the catheter 320can form a ring having a central opening extending therethrough. The tab1364 of the dilator 340 can have an annular detent with a central post.The central post of the tab 1364 can be sized to insert through thecentral opening of the tab 334 such that the ring of the tab 334 isreceived within the annular detent of tab 1364 forming a singulargrasping element for a user to advance and/or withdraw the cathetersystem through the access sheath. The tab 1364 may be affixed to thedilator 340, or may be slideable on the dilator 340 to accommodatedifferent relative positions between the dilator 340 and the spinedcatheter 320.

FIGS. 12A-16 provide additional views of a spined aspiration catheterand dilator system 1300 as described elsewhere herein. FIGS. 12A-12Bshow the spined aspiration catheter 1320 having a dilator 1340 extendingthrough an aspiration lumen 1323 of the distal luminal portion 1322. Asdescribed elsewhere herein, the catheter 1320 can have a proximal spine1330 having a tab 1334 and a distal luminal portion 1322 having anaspiration lumen 1323. The spine 1330 can extend between the distalluminal portion 1322 and the tab 1334. The dilator 1340 can be receivedwithin the aspiration lumen 1323 of the spined catheter 1320. Thedilator 1340 can include a distal dilator portion 1360 and a proximalspine 1362. The dilator portion 1360 can extend between a distal tip1346 of the dilator 1340 to the start of the proximal spine 1362. Whenengaged with the catheter 1320, the dilator portion 1360 of the dilator1340 may extend through an entire length of the distal luminal portion1322 of the catheter 1320 such that the dilator tip 1346 extends a fixeddistance beyond a distal end of the distal luminal portion 1322 of thecatheter 1320 providing a smooth transition for improved tracking. Thedilator tip 1346 can be tapered as described elsewhere herein and can besoft, atraumatic and flexible to the vessel wall to facilitateendovascular navigation to an embolus in a tortuous anatomy compared todilators typically used for percutaneous arterial access, which aremeant to bluntly dissect through tissue and artery wall.

The dilator 1340 is shown in a locked configuration with the catheter1320 configured for improved tracking through a tortuous and oftendiseased vasculature in acute ischemic stroke. The dilator portion 1360can include one or more detents on an outer surface of the dilatorportion 1360. The detents can be located near a proximal end regionand/or a distal end region of the dilator portion 1360. The detents areconfigured to lock with correspondingly-shaped surface features on theinner surface of the lumen 1323 through which the dilator portion 1360extends. The dilator 1340 can include a dilator tab 1364 on a proximalend of the proximal spine 1362 of the dilator 1340, which as discussedabove can be configured to connect and lock with a corresponding featureon the proximal end region of the catheter spine 1330, for example viaone or more detents or other surface features. Thus, the dilator 1340and the catheter 1320 can have more than a single point of lockingconnection between them. The proximal spine 1362 of the dilator 1340 canextend between the dilator portion 1360 and the tab 1364 of the dilator1340. The dilator portion 1360 can be a tubular element as describedelsewhere herein that forms a guidewire lumen running a length of thedilator portion 1360 (and an entire length of the distal luminal portion1322 of the spined catheter 1320). It should be appreciated that theentire dilator 1340 can be tubular element configured to receive aguidewire through the spine 1362 as well as the dilator portion 1360.The proximal end of the dilator portion 1360, i.e., the transitionsection 1326 between the dilator portion 1360 and the proximal spine1362, may include a “step up” to smooth the transition between thedistal luminal portion 1322 of the catheter 1320 and the dilator portion1360 of the dilator 1340. The transition section 1326 can incorporate anangled cut such that there is no abrupt step transition from the sheath1220 inner lumen 1223 to the catheter 1320 inner lumen 1323.Accordingly, the spined aspiration catheter-dilator 1300 may be smoothto the vascular wall it interfaces with.

The proximal spine 1362 of the dilator 1340 may have a similar stiffnessand character as the spine 1330 of catheter 1320. More particularly, oneor both of the spines 1362, 1330 may be stiff and/or kink resistant.Furthermore, one or both of the spines 1362, 1330 may have a stiffnessto allow pushing the distal portions, i.e., the combined distal luminalportion 1322 and dilator portion 1360, through an access sheath or aguide-sheath while producing a very low profile. In an embodiment, oneor both of the spines 1362, 1330 includes a stiff wire.

The catheter tab 1334 and the dilator tab 1364 can be removablyconnected with one another. More particularly, the tabs 1334, 1364 mayhave a locked configuration and an unlocked configuration. In the lockedconfiguration, the dilator tab 1364 can be engaged with the catheter tab1334. In the unlocked configuration, the dilator tab 1364 may bedisengaged from the catheter tab 1334. The dilator tab 1364 may attach,e.g., click or lock into, the catheter tab 1334 in a fashion as tomaintain the relationships of corresponding section of the spineddilator 1340 and the spined catheter 1320 in the locked configuration.Such locking may be achieved by, e.g., using a detent on the dilator tab1364 that snaps into place within a recess formed in the catheter tab1334, or vice versa. In some implementations, the spine 1330 of thespined catheter 1320 can run alongside or within a specialized channelof the dilator spine 1362. The channel can be located along a length ofthe dilator spine 1362 and have a cross-sectional shape that matches across-sectional shape of the catheter spine 1330 such that the spine1330 of the catheter 1320 can be received within the channel and slidesmoothly along the channel bi-directionally. Once the spined catheter1320 and spined dilator 1340 are fixed, the combined system, i.e., thespined aspiration catheter-dilator 1300 may be delivered to a targetsite, for example through the lumen 223 of the access sheath 220described elsewhere herein.

Referring to FIG. 12B, a spined aspiration catheter-dilator 1300 havinga spined catheter 1320 and a spined dilator 1340 in an unlockedconfiguration is illustrated in accordance with an embodiment. When thespined aspiration catheter-dilator 1300 is positioned at the targetsite, as discussed herein, the dilator tab 1364 can be unlocked from thecatheter tab 1334. The spined dilator 1340 may be withdrawn and thespined catheter 1320 may be used, e.g., for aspiration or for wire orballoon delivery.

Referring to FIG. 13 , a cross-sectional view, taken about line A-A ofFIG. 12B, of a spined catheter 1320 coaxially aligned with a spineddilator 1340 is illustrated in accordance with an embodiment. Thecross-section illustrates a portion of the catheter-dilator having thedilator portion 1360 received within the aspiration lumen 1323 of distalluminal portion 1322. The lumen 1323 may have an inner diameter in arange up to 0.072 inches, although a larger or smaller inner diameter ispossible (larger or smaller possible). The wall of the distal luminalportion 1322 may resist kinking or ovalizing to provide maximum diameterfor aspiration. The dilator portion 1360 may be received in the distalluminal portion 1322 in a slip fit. Thus, in an embodiment, an outerdimension of the dilator portion 1360 may be less than the innerdiameter of the distal luminal portion 1322. For example, the lumen 1323may have a diameter of 0.072 inches and the dilator portion 1360 mayhave an outer dimension of 0.070 inches.

Referring to FIG. 14 , a cross-sectional view, taken about line B-B ofFIG. 12B, of a spined catheter 1320 after removal of a spined dilator1340 is illustrated in accordance with an embodiment. The cross-sectionillustrates the distal luminal portion 1322 after the dilator portion1360 has been retracted and/or removed. The distal luminal portion 1322has an inner wall 1321 defining the lumen 1323. The lumen 1323 may becircular, as shown, or may have any other shape. In an embodiment, theeffective diameter of the lumen 1323 ranges up to 0.072 inches.

Referring to FIG. 15A, a spined aspiration catheter-dilator system 1300having a spined catheter 1320 and a spined dilator 1340 in a lockedconfiguration is illustrated in accordance with an embodiment. In anembodiment, the spine 1330 and dilator 1340 may have an outer dimensionthat is substantially similar over an entire length. For example, ratherthan converging to a smaller dimension between the dilator portion 1360and the dilator spine 1362, the dilator spine 1362 may have a samedimension as the dilator portion 1360. Thus, a catheter-dilator having asubstantially same cross-sectional area over at least a majority of itslength may be provided. As discussed above, the spine dilator 1340 andthe spine catheter 1320 may have corresponding tabs 1334, 1364 thatengage in a locked configuration and disengage in an unlockedconfiguration.

Referring to FIG. 15B, a spined aspiration catheter-dilator having aspined catheter 1320 and a spined dilator 1340 in an unlockedconfiguration is illustrated in accordance with an embodiment. Thespined dilator 1340 may be removed from the spined catheter 1320 in amanner similar to that described above. In an embodiment, the spinedaspiration catheter-dilator may have a similar cross-sectional area overa majority of its length, and thus, the shapes of the spined catheter1320 and the spined dilator 1340 may be complimentary. For example, thespine 1330 may have a cross-sectional area along an arc, such as aquarter circle, and thus, a cross-sectional area of the dilator spine1362 may be three quarters of a circle. As such, the spine 1330 mayconform to the dilator spine 1362 to provide an overall cross-sectionalarea of a full circle.

Referring to FIG. 16 , a schematic view of a spined catheter 1320 havinga distal luminal portion 1322 having an inner lumen 1323 located in aneurovascular anatomy is illustrated in accordance with an embodiment.Used in conjunction with an access sheath 1220 having a sheath body 1222and an inner lumen 1232, in an embodiment where the spined catheter 1320reaches the ICA and the distance to embolus E is consistently felt to beless than 20 cm, one would see that the distal luminal portion 1322having a length of 25 cm would allow for an overlap region 1120 with theaccess sheath 1220 to create a seal. The overlap region 1120 may have alength of a few centimeters, and the may vary depending on the distancefrom the embolus E to the distal end of the distal luminal portion 1322,e.g., depending on how far the spined catheter 1320 is advanced relativeto the access sheath 1220.

As described elsewhere herein, the luminal area available for aspirationof the embolus is greater using the spined catheter 1320 as compared toan aspiration system having a conventional large bore catheter in anaccess sheath. More particularly, the combined volume of the luminalarea of the spined catheter 1320 and the luminal area of the accesssheath 1220 proximal to the distal luminal portion 1322 is greater thanthe luminal area of the large bore catheter along the entire length ofthe system. Thus, the likelihood of removing the embolus in a singleaspiration attempt may be increased. More particularly, the stepped upluminal diameter along the spine 1330 may enable a greater aspirationforce to be achieved resulting in improved aspiration of the embolus.The stepped up luminal diameter may also increase the annular areaavailable for forward flushing of contrast, saline, or other solutionswhile devices such as microcatheters or tapered inner members arecoaxially positioned in the spined catheter and access sheath. Thus, theease and ability to perform angiograms during device navigation may beimproved.

The disclosed systems may be supplied with ancillary devices that areparticularly configured to be used with the system. It should beappreciated that reference to one implementation of an access sheathsystem or aspiration catheter system is not intended to be limited andthat the ancillary devices described herein can be used with any of thesystems having any of a variety or combination of features describedherein. For example, where an access sheath is described below it shouldbe appreciated that one or more features of any of the access sheaths oraccess sheath systems described herein can be incorporated. Similarly,where a spined catheter is described below one or more featured of anyof the spined catheters or spined catheter systems described herein canbe incorporated.

In an implementation, the system includes a microcatheter 400 (see FIG.1 ). The microcatheter 400 can be configured to be particularly suitedfor navigation in the cerebral vasculature. The microcatheter 400 may beused in place of the tapered dilator 340 to help navigate the spinedcatheter 320 to the desired site. As such, it may include means at theproximal end to lock the spine 330 to the microcatheter 400, so that sothat the two components (the spined catheter 320 and the microcatheter400) may be advanced as a single unit over the guidewire. In someinstances the microcatheter 400 is advanced ahead of the catheter 320,to provide support as the catheter 320 is advanced, or to cross theocclusion and perform an angiogram distal to the occlusion. In thiscase, the length of the microcatheter 400 can be longer than the spinedcatheter 320 by about 10 to 20 cm. The microcatheter 400 may also beused to deliver a retrievable stent device 500 to the occlusion. In thiscase, the microcatheter 400 can have an inner diameter suitable fordelivery of the retrievable stent device 500, for example, in the range0.021″ to 0.027″ and with a PTFE inner liner. The microcatheter 400 canbe at least about 5-10 cm longer or at least about 5-20 cm longer thanthe overall length of the spined catheter 320 to allow the microcatheter400 to extend beyond the distal end of the aspiration catheter 320during navigation.

In an implementation, the system includes a retrievable stent device 500with a distal expandable section 510, which is sized and configured tobe delivered through the microcatheter 400, as shown in FIG. 9 . Theretrievable stent device 500 may be used in conjunction with the othercomponents of the system to aid in removal of the occlusion. Theretrievable stent device 500 may also be used to quickly restore flow tothe occluded artery during the thrombectomy procedure. Examples ofretrievable stent devices include the Solitaire Revascularization Device(Medtronic) or the Trevo Stentriever (Stryker).

In a method of use, the retrievable stent device 500 is used to assistin bringing thrombus into the catheter 320 during an aspiration step, orclearing the catheter 320 that may become clogged during the aspirationstep. In an implementation, the retrievable stent device 500 isconfigured to be particularly suited for performing these functions. Forexample, as shown in FIG. 10A, the distal end of the expandable portion510 of the device 500 has multiple struts or elements 520 that cometogether at the distal tip to close off the distalmost end, such thatthe device allows blood flow across the device, but captures thethrombus pieces as the device 500 is pulled into the catheter 320, andsubsequently through the catheter 320 and out the distal end.Alternately, the distal end 520 is a filter element or a balloonelement.

In another example, in FIG. 10B, the retrievable stent device 500includes two or more segments with one or more proximal segments 510 aconfigured to be expanded in the catheter distal inner lumen while oneor more distal segments 510 b are expanded across the occlusion as isdone with prior retrievable stent devices. Alternately, as seen in FIG.10C, the retrievable stent device 500 has a very long expandable portion510, such that a proximal portion of the expandable portion may beexpanded in the catheter distal inner lumen while the distal portion isexpanded across the occlusion. In all these implementations, theproximal end of expandable section 510 has minimal structural elementsthat will allow the expandable section to be pulled easily into thelumen of the catheter 320, and out of the access sheath 320, so asminimize impediment of thrombus aspiration through the device. In theseexamples, the expandable portion 510 is still engaged with the clot evenwhen the clot is aspirated into the catheter 320, and if the catheter320 becomes corked, the device 500 is well-positioned to clear the clotwhen it is pulled back. Once the retrievable stent device 500 has beenremoved from the luminal portion 322 of the catheter 320, additionalaspiration can be applied to the site through the catheter 320 if it isstill partially or fully occluded. This step would not be possible ifthe catheter 320 remained clogged; the catheter would have to be removedand cleared outside the patient before being reinserted for additionalaspiration. This configuration of retrievable stent device 500 can beused with either a conventional single lumen aspiration catheter, or aspined aspiration catheter 320.

The implementations of device 500 as shown in FIGS. 10A-10C may be usedwith known thrombectomy devices and methods to address the issue ofcatheters clogging during thrombus aspiration.

In an implementation, the system includes an aspiration source 600, asshown in FIG. 2A or FIG. 3 . The aspiration source 600 can be attachedto the aspiration line 230 on the access sheath 220. Examples ofaspiration source 600 include a syringe or an active aspiration pump.The aspiration source 600 may be connected to a delivery location, suchas a receptacle. The receptacle and source of aspiration 600 may beseparate, such as a mechanical or electromechanical fluid pump whoseoutlet is connected to a blood collection reservoir or may be combinedinto a single device such as a syringe or syringe pump. Alternately, theblood collection reservoir is connected to a source of vacuum such as ahospital vacuum line or an air vacuum pump, and is thus the receptacleas well as the source of aspiration. A filter and/or a check valve maybe coupled with the aspiration source. The pump may be a positivedisplacement pump such as a diaphragm or piston pump, a peristalticpump, centrifugal pump, or other fluid pump mechanism known in the art.

In an implementation, the aspiration source is a variable state ormulti-state aspiration source, and includes a mechanism to control thelevel of aspiration, for example by modifying the vacuum level in thevacuum pump, by modifying the power to the motor of a positivedisplacement, peristaltic or centrifugal pump, or modifying the syringepull back speed in the syringe or syringe pump. Alternately, theaspiration rate may be varied by providing an element with variableresistance to flow, for example parallel flow paths that can switchbetween a high and low flow resistance path, flow orifices or lumensthat can be variably opened, or other means to vary flow resistance. Inan example, the aspiration source is configured to have two levels ofaspiration: a high level of aspiration to be used when the catheter isin contact with the thrombotic material, to aspirate the thromboticocclusion, and a low level of aspiration to be used during steps in theprocedure that are high risk of causing distal emboli, for examplecrossing the lesion or when flow is restored to the vessel when aretrievable stent device is expanded.

In another example, as shown in FIG. 11 , the aspiration source 600further includes a flow sensor 275 that senses flow in the aspirationline 230, coupled to a controller that controls the level of aspiration.The aspiration source 600 can increase in aspiration level when the flowrate is slow and decrease when the flow rate is increased. In thismanner, the force is greatest when the catheter is clogged or partiallyclogged, but decreases to a minimal level when there is free flow toensure protection from distal emboli but limit the volume of aspiratedblood. In this manner, the system optimizes the thrombus aspirationwhile limiting the amount of blood aspirated. Alternately, theaspiration source 600 can include a vacuum gauge. When the flow in thecatheter 320 is blocked or restricted the pump creates a higher level ofvacuum. In this example the aspiration force may be configured to risewhen higher vacuum is detected.

In yet another aspiration source implementation, the aspiration source600 provides a cyclic level of aspiration force, for example, anaspiration force that cycles between a high level of vacuum to a lowerlevel of vacuum at a set frequency, or from a high level of vacuum to novacuum, or from a high level of vacuum to a pressure source. A cyclicaspiration mode may provide a jack-hammer type force on the thrombus andincrease the ability to aspirate the thrombus through the catheter. Thecyclic aspiration force may be enabled through solenoid valves, aprogrammable pump motor, or the like. In an implementation, cyclicaspiration is applied only when clogged or restricted flow is detectedin the aspiration line, either through low flow or high vacuum, asdiscussed above, and at other times, the aspiration source reverts to alow level of flow, or be turned off. This configuration may becontrolled by the user, or controlled automatically via a feedback loopto the aspiration source.

In an implementation, the system includes a mechanism for passivereverse flow that is configured to be connected to the aspiration lineon the access sheath. For example, the aspiration line is connected to alower pressure site such as a central vein, or an external receptacleset to zero or negative pressure.

In an implementation as shown in FIG. 11 , the flush line 236 may beconnected via stopcock 238 to a syringe 286 that may hold saline fluidor radiopaque contrast. Additionally the flush line 236 may be connectedto a flush source 288, for example, a pressurized bag of saline. A valve292 can control flow from the flush source 288 to the flush line 236.When the valve 292 is opened to the flush line 236 a pressurized sourceof fluid is provided. In an implementation, the valve 292 is coupled viaa mechanical or electromechanical coupler 295 to the aspiration source600 such that the valve 292 is only open when the aspiration source 600is on. Alternately, the valve 292 is coupled to a flow sensor 275 in theaspiration line 230, such that the valve 292 is only on when there isflow in the direction towards the aspiration source 600. In theseimplementations, the flow rate of the flush source 288 is configured toflow just enough to keep the proximal extension 240 clear of blood butnot so high as to cause flow to work against the aspiration flow andlimit aspiration of thrombus. An advantage of this implementation isthat the proximal extension 240 remains clear of blood and any emboli orair that is in the proximal extension 240 is clearly visible. Thisprovides a feedback to the user on when and if to flush the catheterwith saline or contrast via syringe 286.

In another implementation, the valve 292 is coupled either mechanicallyor electromechanically to the valve 242 that connects the sheath body222 to the proximal portion 240 of the sheath 220. The coupling 290 canbe configured such that the valve 292 can only be opened when the valve242 is closed. This feature allows the proximal extension 240 to becleared of blood via a flush step, without risk of flushing emboli backthrough the catheter into the vasculature. The coupling 290 may beconfigured in one of several ways For example, the coupling 290 mayalways open the valve 238 when the valve 242 is closed, or the couplingmay prevent the valve 238 from opening unless valve 242 is closed butthat does not automatically open.

In an implementation, the valve 292 is a variable state valve thatallows different levels of flush flow rate. In this example, the valve292 is configured to allow a slow flush when the aspiration source is ona low setting, a higher level of flush when the aspiration source is ona high setting. In an implementation, the valve allows yet a higherlevel of flush when the valve 242 is closed. These configurations allowa continuous removal of debris and/or clear visibility of the proximalportion of the access sheath and minimizes the risk of distal emboli orair entering the vasculature during the steps of the procedure. Forexample, during the step when the distal tip of catheter is beingremoved from the proximal hemostasis valve 234, any clot that wascaptured on the tip of the catheter may be liberated when the catheteris pulled through the valve, but with the continuous flush the liberatedemboli would be flushed into the aspiration line and not remain in thesheath where it might be re-injected into the vasculature, for exampleduring a contrast injection after the catheter is removed.

Again with respect to FIG. 1 , the system 100 may include a kit ofmultiple devices. In an implementation, the kit includes an accesssheath system 200 wherein the access sheath system includes an accesssheath, one or more tapered sheath dilators, and one or more sheathguidewires. In another implementation, the system 100 includes an accesssheath system 200 and one or more spined catheter systems 300 with oneor more inner diameters. In an implementation, the spined cathetersystem 300 includes a spined aspiration catheter 320 and a tapereddilator 340. In an implementation, the spined catheter system 300 alsoincludes a catheter clearing tool 350. In yet another implementation,the system 100 includes an access sheath system 200, a tapered cathetersystem 300, a microcatheter 400, and a retrievable stent device 500.

In an implementation configured for transcarotid access, the kitincludes an access sheath 220, wherein the insertable sheath body 222length is about 23 cm, the proximal extension 240 is about 22 cm, theconnector 226 is about 7 cm and the proximal hemostasis valve 234 isabout 5 cm, for an overall access sheath length of about 57 cm. In animplementation, the kit also includes a spined aspiration catheter 320wherein the catheter distal luminal portion 322 is about 20 cm, thetransition section 326 is about 2-4 cm, and the spine section 330 isabout 65 cm, for an overall spined catheter length of about 88 cm. Inanother implementation, the kit also includes a tapered dilator 340 witha working length of 93 cm. In another implementation, the kit alsoincludes a microcatheter 400 with a working length of about 198 cm and aretrievable stent device 500 with an overall length of 128 cm.

In an implementation configured for transfemoral access, the kitincludes an access sheath system 220, wherein the insertable sheath body222 length is about 90 cm, the proximal extension 240 is about 22 cm,the connector 226 is about 7 cm and the proximal hemostasis valve 234 isabout 5 cm, for an overall access sheath length of about 124 cm. Theproximal portion of the access sheath may be a removable proximalportion 280. In an implementation, the kit also includes a spinedaspiration catheter 320, wherein the catheter distal luminal portion 322is about 20 cm, the transition section 326 is about 2-4 cm, the spinesection 330 is about 132 cm, for an overall spined catheter length ofabout 155 cm. In another implementation, the kit also includes a tapereddilator 340 with a working length of 160 cm. In another implementation,the kit also includes a microcatheter 400 with a working length of about165 cm and a retrievable stent device 500 with an overall length of 195cm.

In another implementation, the kit includes an access sheath 220 with aremovable proximal portion 280, and a single lumen aspiration catheter.In another implementation, the kit includes only the proximal portion280 that can be attached to any introducer sheath suitable for theprocedure. In this implementation, the kit may also include a spinedaspiration catheter 320 or a single lumen aspiration catheter.

In any of these implementations, the kit may also include an aspirationsource, for example a pump, an attachment to a vacuum pump, a syringe, asyringe that is attachable to a syringe pump, or the like. The kit mayalso include means for automatic flushing, for example coupling means290 or 292.

As described elsewhere herein, it should be appreciated that referenceto one implementation of an access sheath system or catheter system isnot intended to be limited and that the kits described herein canincorporate any of the systems and/or ancillary devices described hereinas having any of a variety of features. For example, where an accesssheath is described as being a part of a kit it should be appreciatedthat one or more features of any of the access sheaths or access sheathsystems described herein can be incorporated. Similarly, where a spinedcatheter is described as being part of a kit one or more featured of anyof the spined catheters or spined catheter systems described herein canbe incorporated.

FIGS. 2A and 3 illustrates methods of use. As shown in FIG. 2A, anaccess sheath 220 is inserted using standard vascular access sheath intothe femoral artery, and advanced until the sheath tip is positioned at asite as distal as safely possible in the internal or common carotidartery. In FIG. 3 , the access sheath 220 is inserted directly into thecommon carotid artery, and advanced until the sheath tip is positionedat a site as distal as safely possible in the internal carotid artery.In either scenario, the sheath may be advanced initially to the commoncarotid artery or proximal internal carotid artery, and then the dilatorand is exchanged for a softer dilator before advancing the sheath moredistally into the internal carotid artery. The sheath is then secured tothe patient using a suture through the eyelet on the sheath connector.The sheath aspiration line 230 is connected to an aspiration source 600such as a syringe or aspiration pump. The sheath aspiration line mayalso be connected via a stopcock or stopcock manifold to a forward flushline (such as a pressurized saline bag).

Once the sheath tip is positioned at the desired location, it is securedto the patient. A spined catheter, tapered dilator, and guidewire arepre-assembled in a co-axial configuration and introduced through thesheath proximal hemostasis valve into the carotid artery. The spinedaspiration catheter 320 is advanced through access sheath and positioneduntil the distal tip is at the treatment site. The devices are advancedusing standard interventional techniques until the distal catheter tipis at the proximal face of the occlusion. A mark 332 on the spine 330ensures that there is still an overlap region 120 between the distalluminal portion 322 of the catheter and the access sheath body 222. Atthis point, the tapered dilator 340 and guidewire can be removed. In analternate implementation, a microcatheter 400 is used in place of thetapered dilator 340 to help navigate the catheter 320 to the occlusion.During the procedure, the forward flush is opened to the aspirationlumen to keep the lumen clear before or between periods of aspiration.At any point during device navigation, aspiration may be initiated fromthe aspiration source 600 at a level suitable for distal embolicprotection, for example when the guidewire or microcatheter 400 iscrossing the occlusion.

Once the distal tip of the spined aspiration catheter 320 is at the faceof the clot, aspiration is initiated at a level suitable for aspirationthrombectomy, which is a higher level than for distal embolicprotection. The catheter 320 may remain in aspiration mode against theclot for some period of time, as deemed suitable by the user. Dependingon the results of the aspiration thrombectomy maneuver (as observed byflow though the aspiration line and/or resistance to backwards force onthe spine of the catheter), the user may determine that the clot hasbeen completely aspirated, or if not, the user may choose to move thecatheter 320 back and forth to aspirate the clot in situ, or to slowlyretract the catheter 320 into the sheath 220. If flow is restored to theartery via aspiration of the clot through the catheter 320 and sheath220, a final angiogram may be performed and the catheter 320 can beretracted. If however, thrombus occludes the catheter tip and cannot beremoved, the catheter 320 is pulled back, with some or all of theocclusion attached through suction force to the tip of the catheter 320.

In the latter scenario, aspiration is maintained at the tip of thecatheter 320 the entire time the catheter 320 is being pulled into theaccess sheath 220. Once the catheter 320 has been completely retractedinto the access sheath 220, the catheter 320 can be quickly removed fromthe sheath body 222 while aspiration is maintained on the sheath 220. Itshould be appreciated that the catheter 320 may be withdrawn into thesheath body 222 after extending through the distal opening 219 at thedistal tip of the sheath body 222. Alternatively, the catheter 320 maybe extending through a side opening 219 near a distal end region of thesheath body 222 such that withdrawal of the catheter 320 into the sheathbody 220 occurs through this side opening 219. At some time duringcatheter retraction, depending on if the catheter 320 is clogged withocclusive material, the aspiration level may be changed from a highlevel desirable for aspiration thrombectomy to a lower level desirablefor distal embolic protection. By providing the ability to maintainaspiration continuously from either the catheter tip or the sheath tipor the sheath distal region, and providing the means to changeaspiration levels and maintain asp, the procedure optimizes the abilityto aspiration clot while minimizing distal emboli and minimizing bloodloss from aspiration. If desired, aspiration may also be initiated atthe flush line 236 of the proximal valve 234, to reduce chance of distalembolization during removal of the catheter tip with possibly adheredclot through the proximal valve 234.

The spined aspiration catheter 320 may be removed completely from theproximal hemostasis valve 234 of the sheath 220. Alternately, if theaccess sheath 220 has a proximal extension 240, the distal luminalportion 322 may be pulled into the proximal extension portion 240. Inthe latter scenario, once pulled in, the catheter 320 and sheath 220 maybe flushed to remove potential embolic material without removing thecatheter 320 completely from the sheath 220. A vigorous flush from theproximal valve flush line 236 simultaneous with aspiration from theaspiration line 230 creates a flush environment for the catheter 320 andsheath 220. If desired, a catheter clearing tool 350 may be insertedinto the sheath proximal valve 234 and used at this time to clear theinner lumen 323 of the catheter 320. If the access sheath 220 has aconnector valve 242, the proximal portion 240 may be closed off from thesheath body 222 during this stage, so that there is no risk of flushingembolic material into the sheath body 222 and thence into the artery.

Alternately, the valve 242 may be closed off and aspiration paused whilethe proximal valve 242 is opened or removed and the catheter 320 iscompletely removed from the sheath 220. Closing the valve 242 limits theblood loss from the sheath 220 as the catheter 320 is removed. Thecatheter 320 may then be flushed onto the table or into a bowl or otherreceptacle, using the cleaning tool 350. The proximal extension portion240 may also be flushed by providing a flush source 288 from theproximal valve flush line 236 simultaneous with aspiration from theaspiration line 230, or by opening a side port on the aspiration line230 to flush to the table or into a bowl or other receptacle. Ifdesired, an angiogram may be performed to assess flow through thetreated artery. If the procedure dictates, the catheter 320 or anothercatheter may be re-advanced as above over a guidewire and tapereddilator 340 or microcatheter 400 to the site of the occlusion to attemptanother aspiration thrombectomy step. The flushing of the catheters andproximal extension portion 240 of the access sheath 220 minimizing therisk of distal emboli during these subsequent steps.

In another exemplary method, a retrievable stent device 500 can be usedin conjunction with aspiration to remove the thrombotic occlusion. FIG.9 illustrates this method of use through either a transcarotid ortransfemoral access site. In this scenario, the access sheath 220 can bepositioned as above and advanced until the sheath tip is positioned at asite as distal as safely possible in the internal carotid artery. Thespined aspiration catheter 320 can be then pre-loaded onto amicrocatheter 400 and guidewire, and the co-axial assembly can beintroduced via the access sheath 220 into the carotid artery andadvanced into the cerebral vasculature. The microcatheter 400 andguidewire can be advanced across occlusion. The tip of the spinedaspiration catheter 320 can be advanced as distal as possible butproximal to the clot.

At this point, the guidewire can be removed and the retrievable stentdevice 500 inserted through the microcatheter 400 until it too ispositioned across the occlusion. The microcatheter 400 can be pulledback to deploy the stent. At any point during device navigation,aspiration may be initiated from the aspiration source at a levelsuitable for distal embolic protection, for example when the guidewireor microcatheter 400 is crossing the occlusion, or prior to stentdeployment. By having aspiration initiated before stent deployment, anyemboli that was liberated while crossing the lesion is not carrieddownstream on restoration of flow in the artery, but is rather capturedinto the catheter tip. While the retrievable stent device 500 isdeployed, aspiration may be maintained. It is typically deployed forseveral minutes before retraction of the stent is attempted, to maximizethe engagement of the stent struts to the occlusion. Then, theretrievable stent device 500 can be pulled into the spined catheter 320and continued to be retracted until it has been completely removed fromthe proximal valve of the access sheath 220.

Alternately, the stent device 500 can be pulled into the distal portionof the spined catheter 320, and the stent device 500 and spined catheter320 can be pulled back together out of the access sheath 220. Aspirationmay be increased to a higher level during stent and/or catheterretraction steps, to optimize aspiration of clot and minimize distalemboli. If the access sheath 220 has a proximal extension 240 with avalve on the connector, the device 500 can be pulled into the proximalextension 240 and the valve closed, and then the proximal hemostasisvalve 234 may be opened widely and the stent device 500 or the stentdevice/spined catheter combination may be pulled out. The proximalextension section 240 may then be flushed via the valve flush line 236and the aspiration line 230 before the same or alternate devices arereinserted for another thrombectomy attempt, if the procedure dictates.

Alternately after placement of an aspiration catheter 320, a long orsegmented stent retriever 500 can be positioned as above with amicrocatheter 400 such that part of the expandable portion 510 is acrossthe thrombus and part is in the distal segment 322 of the catheter 320,and then expanded. After the expandable portion 510 is expandedaspiration can be initiated so that thrombus either is suctionedcompletely out of the vessel and catheter 320 into the aspiration source600, or is suctioned into the distal tip and/or distal lumen 323 of thecatheter 320. At that point, the long or segmented stent retriever 500can be carefully pulled into the catheter 320, while maintainingaspiration. During this time clot that has been clogging the catheter320 and/or debris that is liberated during this step should be aspiratedinto the catheter 320. Complete removal of the stent retrieval device500 from the working channel 323 of the catheter 320 should free up thelumen 323 from occlusive material.

In any of these scenarios, the aspiration source may be a variable ormulti-state aspiration source that is configured to maximize theaspiration force on the thrombotic occlusion while minimizing blood lossduring periods of free flow in the catheter.

In another exemplary method, the access sheath 220 has an occlusionballoon 246. As seen in FIG. 7 , the balloon 246 may be inflated duringsteps of the procedure that are high risk for distal emboli, for exampleretraction of the stent device 500 or the spined catheter 320 withadhered clot. The balloon 246 has the effect of stopping antegrade flowand increasing the force of aspiration in the carotid artery, thusincreasing the aspiration of clot and reducing the risk of distalemboli.

In another exemplary method, the access sheath 220 has an expandabledistal tip. In this method, the distal tip may be expanded sometimeafter the access sheath tip has been positioned at the desired site, butbefore retraction of the spined catheter 320 into the access sheath 220.This method would reduce the chance of distal emboli caused by therelease of clot that was adhered to the distal tip of the spinedcatheter 320, as the distal tip is pulled into the tip of the sheath220. Instead, the access sheath tip that is expanded or flared out actsas a funnel to capture the entire clot.

In another exemplary method and as discussed briefly above, the accesssheath 1220 has a side opening 1219 (best shown in FIG. 12C). In thismethod, the spined catheter 1320 having a spined dilator 1340 extendingthrough lumen 1323 of the distal luminal portion 1322 of the catheter1320 can be advanced distally through the lumen 1223 of the accesssheath 1220 towards the distal end region of the sheath body 1222. Thedistal tip of the distal luminal portion 1322 of the spined catheter1320 (which may having the spined dilator extending through the distalluminal portion 1322 and forming a distal-most end to the cathetersystem) may exit the lumen 1223 via the side opening 1219 and then befurther advanced distally beyond the distal tip of the access sheath1220. A ramp feature 1217 or other internal feature can be incorporatedat a distal end region of the lumen 1223 to provide a surface againstwhich the tip of the dilator can be deflected to guide the catheter 1320away from a longitudinal axis A of the lumen 1223 of the sheath body1222 towards the side opening 1219 to achieve a smooth transition orexit from the lumen 1223. The distal tip 1346 of the dilator 1340 canabut against the ramp feature 1217 and be directed at a slightangulation away from the longitudinal axis of the sheath body 1222towards the side opening 1219. As described elsewhere herein, the sheathbody 1222 and thus the side opening 1219 can be rotated around thelongitudinal axis A such that the one or more side openings 1219 arepositioned to allow for distal extension of the catheter 1320 from theside openings 1219 in a desired direction relative to the longitudinalaxis A of the sheath 1220. This will often be dictated by the anatomyencountered by the operator. Also as mentioned elsewhere herein, anoverlap region 1120 is formed between the distal luminal portion 1322 ofthe catheter and the access sheath body 1222. A sealing element 1336 canbe positioned on the external surface of the distal luminal portion1322, for example, near a proximal end region of the distal luminalportion 1322 and may be located within the overlap region 1120. The sealformed can allow for full transmission of aspiration force through thecontiguous lumen formed by the lumen 1323 of the luminal portion 1322and the lumen 1223 of the access sheath body 1222 upon withdrawal of thedilator 1340 from the lumen 1323 of the luminal portion 1322.

In another exemplary method, the aspiration source 600 is connected to ablood collection reservoir that maintains the integrity of the blood insuch a way that the blood can be safely returned to the patient at theconclusion of the thrombectomy portion of the procedure, either directlyor through subsequent treatment of the blood such as cell washing and/orblood filtration. In another exemplary method, the aspiration source isconnected to a blood shunt that is connected in turn to a device such asa venous sheath or a venous return catheter that enables blood to bereturned to the patient during the procedure and not requiring a bloodreservoir. In another exemplary method, the blood is collected in areservoir and subsequently discarded at the end of the procedure.

In another exemplary method, the access sheath 1220 is delivered asdescribed elsewhere herein from a femoral insertion site to a right orleft subclavian artery or an external carotid artery. The access sheath1220 may be delivered to a carina of a bifurcation between a targetvessel having the embolus, such as the internal carotid artery (ICA),and another vessel, such as the external carotid artery (ECA). Once theaccess sheath 1220 is in position a working device such as a splinedaspiration catheter 1320 can be delivered through the lumen 1223 of theaccess sheath 1220 into the target vessel. The lumen 1223 of the accesssheath 1220 and the lumen 1323 of the catheter 1320 are contiguous andform a stepped up diameter for aspiration as described elsewhere herein.An overlap region 1120 is maintained between the catheter 1320 extendingdistally from the lumen 1223 of the access sheath 1220. It should beappreciated that the catheter 1320 can extend distally from the lumen1223 of the access sheath 1220 through an opening 1221 at the distal tipof the access sheath 1220 or a side opening 1119 near the distal regionof the access sheath 1220. The body 1222 of the access sheath 1220 maybe oriented to provide optimum placement of the side opening 1119relative to the anatomy. The overlap region 1120 between the distalluminal portion 1322 of the catheter 1320 and the access sheath body1222 can create a seal and allow for full transmission of aspiratingforce through the contiguous lumen formed by the lumen 1323 of theluminal portion 1322 and the lumen 1223 of the access sheath body 1222,as well as providing a seal for delivery of fluids to the target vesselsuch as angiographic contrast injection, saline, one or more drugs orother materials directly into the neurovascular anatomy. The spinedaspiration catheter 1320 can create a more powerful aspiration force byallowing for the working lumen 1223 of the access sheath 1220 to providea majority of the aspiration column. As described elsewhere herein, thedimension of the lumen 1323 of the distal luminal portion 1322 of theaspiration catheter 1320 may be less than the diameter of the lumen 1223of the access sheath 1220, which is reduced only by a diameter of thespine 1330 extending therethrough. The increased diameter of the lumencan create a larger aspiration column than, e.g., an aspiration columnof a large bore catheter having a similar overall length. The spinedaspiration catheter 1320 may also be used as a supportive deliverycatheter, for example, where the operator wants to reach the petrouscarotid or other hard to reach landmarks within the cerebralvasculature. More particularly, after delivering the spined aspirationcatheter 1320 into the target vessel through the working lumen 1223 ofthe access sheath 1220, a secondary working device such as a guidewire,microcatheter, stent retriever, etc. may be delivered through the lumen1323 into a more distal anatomy to perform other procedural operationsas described elsewhere herein.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of an invention that is claimed orof what may be claimed, but rather as descriptions of features specificto particular implementations. Certain features that are described inthis specification in the context of separate implementations can alsobe implemented in combination in a single implementation. Conversely,various features that are described in the context of a singleimplementation can also be implemented in multiple implementationsseparately or in any suitable sub-combination. Moreover, althoughfeatures may be described above as acting in certain combinations andeven initially claimed as such, one or more features from a claimedcombination can in some cases be excised from the combination, and theclaimed combination may be directed to a sub-combination or a variationof a sub-combination. Similarly, while operations are depicted in thedrawings in a particular order, this should not be understood asrequiring that such operations be performed in the particular ordershown or in sequential order, or that all illustrated operations beperformed, to achieve desirable results. Therefore the spirit and scopeof the appended claims should not be limited to the description of theimplementations contained herein.

What is claimed is:
 1. A system configured to facilitate advancement ofa catheter through a blood vessel, the system comprising: a catheterhaving a lumen having an inner diameter; and a dilator comprising: afirst section comprising a metal hypotube, wherein the first section hasa maximum outer diameter; a second section distal of the first section,the second section being more flexible than the first section; a distaltip of the second section, a distal tip outer diameter being smallerthan a second section outer diameter, wherein the second section outerdiameter is smaller than the inner diameter of the catheter and islarger than and tapers down to the maximum outer diameter of the firstsection, and wherein a distal-most end of the distal tip defines adistal opening; and a single lumen extending through the first sectionand the second section to the distal opening, wherein the single lumenextending through the first section and the second section of thedilator has a maximum inner diameter of 0.024 inch; wherein the secondsection outer diameter is configured to minimize open space between thedilator and the lumen of the catheter when the dilator is disposedwithin the lumen of the catheter to facilitate advancement of thecatheter through the blood vessel, wherein the open space includes a gapbetween the dilator and the lumen of the catheter to allow the dilatorto move within and beyond the catheter; wherein the second section ispositioned at least partially, distally beyond a distal end of thecatheter when the dilator is disposed within the lumen of the catheter,and wherein the gap is formed by a difference between the second sectionouter diameter and the inner diameter of the lumen of the catheter whenthe dilator is disposed within the lumen of the catheter; wherein thedistal tip has a length and a flexibility configured to advance throughthe petrous portion of the internal carotid artery.
 2. The system ofclaim 1, wherein, when the dilator is disposed within the lumen of thecatheter, the second section outer diameter is 0.003″ smaller than theinner diameter of the lumen of the catheter.
 3. The system of claim 1,wherein the second section outer diameter is 0.070 inches.
 4. The systemof claim 1, wherein the second section includes at least one markerband.
 5. The system of claim 1, wherein the maximum inner diameter isconsistent throughout an entire length of the dilator.
 6. The system ofclaim 1, wherein the distal tip includes a marker band.
 7. The system ofclaim 1, wherein the second section outer diameter is 0.070 inches andthe inner diameter of the catheter is 0.072 inches.
 8. The system ofclaim 1, wherein a proximal end of the first section is coupled to aluer adaptor or a tab.
 9. The system of claim 1, wherein the secondsection is formed of polymer.
 10. The system of claim 1, wherein alength of the distal tip is 1.5 cm to 3 cm.
 11. A system configured tofacilitate advancement of a catheter through a blood vessel, the systemcomprising: a catheter having a lumen having an inner diameter; and adilator comprising: a first section comprising a hypotube, wherein thefirst section has a maximum outer diameter; a second section distal ofthe first section, the second section being more flexible than the firstsection; a distal tip of the second section having a taper that providesa smooth transition between the catheter and a guidewire positionedwithin the dilator, wherein a length of the distal tip taper is 1.5 cmto 3 cm; and a single lumen extending through the first section andsecond section to a distal opening defined by a distal-most end of thedistal tip, the single lumen having a maximum inner diameter of 0.024inch; wherein a second section outer diameter is configured to minimizeopen space between the dilator and the lumen of the catheter when thedilator is disposed within the lumen of the catheter to facilitateadvancement of the catheter through the blood vessel, wherein the openspace includes a gap between the dilator and the lumen of the catheterto allow the dilator to move within and beyond the catheter; wherein thesecond section is positioned at least partially, distally beyond adistal end of the catheter when the dilator is disposed within the lumenof the catheter, and wherein the gap is formed by a difference betweenthe second section outer diameter and the inner diameter of the lumen ofthe catheter when the dilator is disposed within the lumen of thecatheter; wherein the distal tip has a length and a flexibilityconfigured to advance through the petrous portion of the internalcarotid artery, and wherein the second section outer diameter is largerthan and tapers down to the maximum outer diameter of the first section.12. The system of claim 11, wherein when the dilator is disposed withinthe lumen of the catheter, the second section outer diameter is 0.003inch smaller than the inner diameter of the lumen of the catheter. 13.The system of claim 11, wherein the second section outer diameter is0.070 inch.
 14. The system of claim 11, wherein the second sectionincludes at least one marker band.
 15. The system of claim 11, whereinthe maximum inner diameter is consistent throughout an entire length ofthe dilator.
 16. The system of claim 11, wherein the distal tip includesa marker band.